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Robotics Interview questionsA list of top frequently asked Robotics Interview Questions and answers are given below.1) What do you understand by the term, the robotics?The robotics is a combined branch of engineering and science which deals with the study of development, operation, and control of intelligent robots. The robotics is a part of Artificial intelligence.The robotics technology is used for the development of machines which can perform a complex human task in a very efficient way.2) What is a robot?A robot is a programmable machine which is capable of doing complex tasks automatically with precision and efficiency. The robots can be guided by external or internal input to perform any work.Play VideoA robot can be designed as resembled as human or it can be designed as a standard machine look alike.3) Which was the first industrial robot?The first industrial robot was "Unimate." It was manufactured by American inventor George Devol in 1950 and used in 1954. It was produced for the transportation of die casting form an assembly line and then welding on auto bodies.4) What are the Laws of the robotics?The "Three Laws of the robotics" also known as "Asimov's law," given by the author Isaac Asimov. The three laws are given below:First law: A the robot may not injure a human being or, through inaction, allow a human being to come to harm.Second law: A the robot must obey the orders given it by human beings except where such orders would conflict with the First Law.Third law: A the robot must protect its own existence as long as such protection does not conflict with the First or Second Laws.After that Asimov also added one more law which precedes the other laws:Zeroth law: A the robot may not harm humanity, or, by inaction, allow humanity to come to harm.5) List the name of the areas where the robotics can be applied?Now a day's the robotics can be applied to most of the areas to provide efficient work with the highest precision and in less time. So there is an overview of areas where robots can be applied in day to day life as well.Military AreaIndustrial AreaAgriculture IndustriesDomestic AreasMedical AreasResearches6) What do you understand by "humanoid robot"?A robot which looks like overall as a Human body is known as a Humanoid robot. A Humanoid robot can have human facial expressions with the features. There are two types of the Humanoid robot to resemble as male and female:Android Humanoid: They are built to resemble a male bodyGynoids Humanoid: They are made to resemble a female body.A humanoid robot is entirely an automatic robot which can interact with the Humans and also can react according to the surrounding.Sophia is a first humanoid which has also got citizenship from the country of Saudi Arabia.7) What are the basic aspects of the robotics?The basic aspects of the robotics to create a robot are given below:Electrical/electronic components- The robotics required electrical and electronic components as power supply, sensors, and microcontroller and motors circuits.Mechanical equipment- The robotics required mechanical equipment for giving shape or designing the body of a robotComputer programs- The robotics also includes computer programs to provide the instructions to the robot as what type of task, when it should be done, how it should be done, etc. Robo ML, ROBOFORTH, XRCL, and visual programming are the programming languages which are used in the robotics.8) What are the components of a robot?There are the basic components of a robot which are given below:Power supply- Power supply is the main components for the run of any device or machine. So a robot also takes energy from the power supply to perform a task. It can be provided from the batteries, hydraulic, solar power or pneumatic power sources.Actuators- Actuators are the devices which convert energy into movement.Electric motors (DC/AC) - Motors are used to convert electrical energy into mechanical energy. Most of the robots used these motors to provide various type of movements to their parts. Brushless and brushed DC motors used in portable the robots and AC motors used in industrial the robots.Sensors- Sensors are used to sense the changes in surrounding and produce a signal. Hence the robots are also equipped with the various types of sensors to detect the environment and responded accordingly.Controller- Controller is the brain of a robot, which controls and co-ordinate with all parts of the robot. And with the help of the controller, the robot can perform all the assigned task. A Microprocessor is a core part of the controller, which takes various signals as Input and generate a corresponding output signal.9) Why do we use robots in the industry?There are the following reasons to use the robots in industry:The robots are used in industry as the robots can perform a task with the highest precision and efficiency.The robots can be operated 24/7 for continues production.The robots can perform some dangerous tasks in the industry.The robots are cost-effective concerning the industry.10) What is AI? Why do we implement AI in the robots?Artificial intelligence is a technology which can develop intelligent devices that can react and work as a human being. AI includes:Speech recognitionLearningProblem-solvingPlanningImplementation of AI in the robots makes a robot intelligent which can perform a complex task, and it can sense the environment and react accordingly.11) What are various types of sensors used in the robotics?There are the following sensors which can be used in the robotics:Light sensors- A light sensor detect light and create a voltage difference, which is equivalent to the light intensity fall on the sensor.The two main Light sensors which used in the robotics are:Photovoltaic cellsPhoto-resistor sensorSound sensors- This sensors are microphones which detects sound and return a voltage difference equivalents to the level of sound. Example of a sound sensor is: Instruct a robot by clap.Temperature sensor- Temperature sensors sense the change in temperature of the surrounding. It provides a voltage difference equivalent to a change in temperature occurred.Example of temperature sensor IC's are LM34, LM35, TMP35, TMP36, and TMP37.Proximity sensor- Proximity sensor can sense any nearby object without any physical contact. Following are the type of proximity sensor used in the robotics:Infrared (IR) Transceivers,Ultrasonic SensorPhoto-resistor sensorAcceleration Sensor- Accelerometer is a device which detects the acceleration and can tilt accordingly.Navigation sensor- These are the sensors which are used to identify the position of the robot. Some of the navigation sensors are:GPS (global positioning system)Digital Magnetic compassLocalization12) What is a robot Locomotion?The robot locomotion is a group of methods which a robot used to transport itself from one place to another place. There are various types of robot locomotion, which are given below:-WalkingRunningRollingHoppingSwimmingSlitheringHybrid13) What is Autonomous robot?A type of robot which can perform any task with autonomy is called an Autonomous robot. An autonomous robot can do work with its own decision without human interaction.14) What is, "human-robot interaction"?Human-robot interaction is a field of study which defines an interaction or communication between a robot and Human. The "Three Laws of The robotics" are given on HRI, which defines a safe interaction between a human and a robot.15) How to send information from the robot sensors to the robot controllers?We can send any information from the robot sensor to the robot controller through the signal.16) What is the Pneumatic System in The robotics?A Pneumatic system is used to drive a machine by using compressed gases. In the robotics, servo motors and electric motors can be replaced by a pneumatic system.A pneumatic system consists of a cylinder piston which can move up and down direction to create pressure.17) Name the basic unit of a robot which can be programmed to give instructions to the robot?The controller is the basic unit of a robot which can be programmed and it can give all type of instructions to perform any tasks.18) What is the degree of freedom in the robotics? How can it be determined?The Degree of freedom in the robotics defines the freedom of movement of the mechanical parts of a robot. It defines the modes by which a machine can move.The Degree of Freedom can be determined as the number of movable joints in the base, the arm, and the end effectors of the robot.19) What is PROLOG used in Artificial intelligence?PROLOG is an acronym for Programming logic.PROLOG is a high-level programming language used primarily in Artificial intelligence, and It consists of the list of rules and factPROLOG is called a declarative programming language20) What is LISP?LISP stands for List programmingLISP mainly used for Artificial intelligence because it can process symbolic information with efficiency.21) What are the axes of movement of the robot?Wrist rotationX-Y coordinate motionElbow rotation22) What do you understand by numerical control?Numerical control is a process of controlling the machine with the help of a computer or sets of instructions.With the help of numerical control, we can automate the machines.23) What is Servo controlled robot?A servo controlled robot is one which works on the servo mechanism. Servo controlled robots are consist of servo motors which processed by the signals. A servo controlled robot can accelerate, that means these robots can change their speed at a different point.24) Name of the industry which highly used the robots?The Automobile industry is an industry which highly used robots for production.25) What are actuators in the robotics?Actuators are the electromechanical device which converts the electric energy into mechanical energy. Actuators can generate motion in each part of the robot.26) What types of motors used in industrial robots?There are various types of motors available, but we can choose a motor for the robotics as per the use of an area. The motor used will depend on how and where a robot is to be used. But there are some common motors which can be used in industrial robotics:Servo MotorsDC/AC motorsStepper MotorsBelt drive motorArm adapted motors.27) What is continuous-path control in the robotics?When we program a robot for physically move through the trajectory or an irregular path exactly then such type of control is called as Continuous-path control in robotics.28) If we wanted to add two number a and b, then how it can be written in LISP language?If we wanted to add two numbers a and b, then it can be written as (+a b) in LISP language.29) What is the use of the function (copy-list ) in LISP?This function is used to return the copy of the defined list.30) What is the Future of The robotics?There are the following areas where the robotics can be used vastly in futureThe robotics can be used for e-commerceThe robotics can be raised with cloud-based software which will define new skills in the robotsThe robotics can be used more than the industries.The robotics can be used in the medical field31) What are industrial robots? Explain the various types of Industrial robots?Industrial robots are those robots which mainly work for manufacturing and production in industries.There are various types of robots which are being used in multiple areas depending on their work, and the following are the description of some industrial robots:Cartesian: Cartesian robot applies the Cartesian coordinate system(X, Y, and Z). These type of the robots have three linear joints. They also may have a wrist which can provide a rotational movement.Polar: The Polar robot is a type of robot which can consist of a rotatory base with an elevation pivot. The polar robot has only one arm which can perform the various task.SCARA: SCARA stands for "Selective Compliance Assembly Robot Arm." Sacra robot can do three linear movements with a vertical motion. It is fixed at the Z axis and flexible in XY axes.Delta: These robots are the shape of a spider which has parallel arms connected to the universal joints.Cylindrical: Cylindrical robot has a rotatory joint for the rotational transaction and a prismatic joint for performing a linear movement.Articulated: Articulated robots have rotatory joints which can range from simple two joints structure to a complex structure with 10 or more joints.32) What is a microcontroller? What is the use of the microcontroller in the robotics?A Microcontroller is a small programmable integrated chip which is used in the embedded system. It consists of a processor, memory with I/O peripherals.In robotics, the microcontroller is used as "brain" for the robot. It controls all the actions performed by the robot. It also gives instructions to a robot to perform any task.
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A list of top frequently asked TypeScript Interview Questions and answers are given below.1) What is Typescript?TypeScript is a free and open-source programming language developed and maintained by Microsoft. It is a strongly typed superset of JavaScript that compiles to plain JavaScript. It is a language for application-scale JavaScript development. TypeScript is quite easy to learn and use for developers familiar with C#, Java and all strong typed languages.TypeScript can be executed on Any browser, Any Host, and Any Operating System. TypeScript is not directly run on the browser. It needs a compiler to compile and generate in JavaScript file. TypeScript is the ES6 version of JavaScript with some additional features.2) How is TypeScript different from JavaScript?TypeScript is different from JavaScript in the following manner:Play VideoxSNJavaScriptTypeScript1It was developed by Netscape in 1995.It was developed by Anders Hejlsberg in 2012.2JavaScript source file is in ".js" extension.TypeScript source file is in ".ts" extension.3JavaScript doesn't support ES6.TypeScript supports ES6.4It doesn't support strongly typed or static typing.It supports strongly typed or static typing feature.5It is just a scripting language.It supports object-oriented programming concept like classes, interfaces, inheritance, generics, etc.6JavaScript has no optional parameter feature.TypeScript has optional parameter feature.7It is interpreted language that's why it highlighted the errors at runtime.It compiles the code and highlighted errors during the development time.8JavaScript doesn't support modules.TypeScript gives support for modules.9In this, number, string are the objects.In this, number, string are the interface.10JavaScript doesn't support generics.TypeScript supports generics.To know more click here.3) Why do we need TypeScript?We need TypeScript:TypeScript is fast, simple, and most importantly, easy to learn.TypeScript supports object-oriented programming features such as classes, interfaces, inheritance, generics, etc.TypeScript provides the error-checking feature at compilation time. It will compile the code, and if any error found, then it highlighted the errors before the script is run.TypeScript supports all JavaScript libraries because it is the superset of JavaScript.TypeScript support reusability by using the inheritance.TypeScript make app development quick and easy as possible, and the tooling support of TypeScript gives us autocompletion, type checking, and source documentation.TypeScript supports the latest JavaScript features including ECMAScript 2015.TypeScript gives all the benefits of ES6 plus more productivity.TypeScript supports Static typing, Strongly type, Modules, Optional Parameters, etc.4) List some features of Typescript?To know more click here.5) List some benefits of using Typescript?TypeScript has the following benefits.It provides the benefits of optional static typing. Here, Typescript provides types that can be added to variables, functions, properties, etc.Typescript has the ability to compile down to a version of JavaScript that runs on all browsers.TypeScript always highlights errors at compilation time during the time of development whereas JavaScript points out errors at the runtime.TypeScript supports strongly typed or static typing whereas this is not in JavaScript.It helps in code structuring.It uses class-based object-oriented programming.It provides excellent tooling supports with IntelliSense which provides active hints as the code is added.It has a namespace concept by defining a module.6) What are the disadvantages of TypeScript?TypeScript has the following disadvantages:TypeScript takes a long time to compile the code.TypeScript does not support abstract classes.If we run the TypeScript application in the browser, a compilation step is required to transform TypeScript into JavaScript.Web developers are using JavaScript from decades and TypeScript doesn?t bring anything new.To use any third party library, the definition file is must. And not all the third party library have definition file available.Quality of type definition files is a concern as for how can you be sure the definitions are correct?7) What are the different components of TypeScript?The TypeScript has mainly three components. These are-LanguageThe language comprises elements like new syntax, keywords, type annotations, and allows us to write TypeScript.CompilerThe TypeScript compiler is open source, cross-platform, and is written in TypeScript. It transforms the code written in TypeScript equivalent to its JavaScript code. It performs the parsing, type checking of our TypeScript code to JavaScript code. It can also help in concatenating different files to the single output file and in generating source maps.Language ServiceThe language service provides information which helps editors and other tools to give better assistance features such as automated refactoring and IntelliSense.To know more click here.8) Who developed Typescript and what is the current stable version of Typescript?The typescript was developed by Anders Hejlsberg, who is also one of the core members of the development team of C# language. The typescript was first released in the month of October 1st, 2012 and was labeled version 0.8. It is developed and maintained by Microsoft under the Apache 2 license. It was designed for the development of a large application.The current stable version of TypeScript is 3.2 which was released on September 30, 2018. Typescript compiles to simple JavaScript code which runs on any browser that supports ECMAScript 2015 framework. It offers support for the latest and evolving JavaScript features.9) Tell the minimum requirements for installing Typescript. OR how can we get TypeScript and install it?TypeScript can be installed and managed with the help of node via npm (the Node.js package manager). To install TypeScript, first ensure that the npm is installed correctly, then run the following command which installs TypeScript globally on the system.$ npm install -g typescript It installs a command line code "tsc" which will further be used to compile our Typescript code. Make sure that we check the version of Typescript installed on the system.Following steps are involved for installing TypeScript:Download and run the .msi installer for the node.Enter the command "node -v" to check if the installation was successful.Type the following command in the terminal window to install Typescript: $ npm install -g typescriptTo know installation process click here.10) List the built-in types in Typescript.The built-in data types are also known as primitive data types in Typescript. These are given below.Number type: It is used to represent number type values. All the numbers in TypeScript are stored as floating point values.Syntax: let identifier: number = value;String type: It represents a sequence of characters stored as Unicode UTF-16 code. We include string literals in our scripts by enclosing them in single or double quotation marks.Syntax: let identifier: string = " ";Boolean type: It is used to represent a logical value. When we use the Boolean type, we get output only in true or false. A Boolean value is a truth value that specifies whether the condition is true or not.Syntax: let identifier: bool = Boolean value;Null type: Null represents a variable whose value is undefined. It is not possible to directly reference the null type value itself. Null type is not useful because we can only assign a null value to it.Syntax: let num: number = null;Undefined type: It is the type of undefined literal. The Undefined type denotes all uninitialized variables. It is not useful because we can only assign an undefined value to it. This type of built-in type is the sub-type of all the types.Syntax: let num: number = undefined;Void type: A void is the return type of the functions that do not return any type of value. It is used where no datatype is available.Syntax: let unusable: void = undefined;To know TypeScript datatypes in detail click here.11) What are the variables in Typescript? How to create a variable in Typescript?A variable is the storage location, which is used to store value/information to be referenced and used by programs. It acts as a container for value in a program. It can be declared using the var keyword. It should be declared before the use. While declaring a variable in Typescript, certain rules should be followed-The variable name must be an alphabet or numeric digits.The variable name cannot start with digits.The variable name cannot contain spaces and special character, except the underscore(_) and the dollar($) sign.We can declare a variable in one of the four ways:Declare type and value in a single statement. Syntax: var [identifier] : [type-annotation] = value;Declare type without value. Syntax: var [identifier] : [type-annotation];Declare its value without type. Syntax: var [identifier] = value;Declare without value and type. Syntax: var [identifier];To know more in detail click here.https://www.javatpoint.com/typescript-variables12) How to compile a Typescript file?Here is the command which is followed while compiling a Typescript file into JavaScript.$ tsc For example, to compile "Helloworld.ts."$ tsc helloworld.ts The result would be helloworld.js.13) Is it possible to combine multiple .ts files into a single .js file? If yes, then how?Yes, it is possible. For this, we need to add --outFILE [OutputJSFileName] compiling option.$ tsc --outFile comman.js file1.ts file2.ts file3.ts The above command will compile all three ".ts"file and result will be stored into single "comman.js" file. In the case, when we don't provide an output file name as like in below command.$ tsc --outFile file1.ts file2.ts file3.ts Then, the file2.ts and file3.ts will be compiled, and the output will be placed in file1.ts. So now our file1.ts contains JavaScript code.14) Is it possible to compile .ts automatically with real-time changes in the .ts file?Yes, it is possible to compile ".ts" automatically with real-time changes in the .ts file. This can be achieved by using --watch compiler optiontsc --watch file1.ts The above command first compiles file1.ts in file1.js and watch for the file changes. If there is any change detected, it will compile the file again. Here, we need to ensure that command prompt must not be closed on running with --watch option.15) What do you mean by interfaces? Explain them with reference to Typescript.An Interface is a structure which acts as a contract in our application. It defines the syntax for classes to follow, it means a class that implements an interface is bound to implement all its members. It cannot be instantiated but can be referenced by the class object that implements it. The TypeScript compiler uses interface for type-checking (also known as "duck typing" or "structural subtyping") whether the object has a specific structure or not.Syntax:interface interface_name { // variables' declaration // methods' declaration } The interface just declares the methods and fields. It cannot be used to build anything. Interfaces need not be converted to JavaScript for execution. They have zero runtime JavaScript impact. Thus, their only purpose is to help in the development stage.16) What do you understand by classes in Typescript? List some features of classes.We know, TypeScript is a type of Object-Oriented JavaScript language and supports OOPs programming features like classes, interfaces, etc. Like Java, classes are the fundamental entities which are used to create reusable components. It is a group of objects which have common properties. A class is a template or blueprint for creating objects. It is a logical entity. The "class" keyword is used to declare a class in Typescript.Example:class Student { studCode: number; studName: string; constructor(code: number, name: string) { this.studName = name; this.studCode = code; } getGrade() : string { return "A+" ; } } Features of a class are-InheritanceEncapsulationPolymorphismAbstraction17) Is Native Javascript supports modules?No. Currently, modules are not supported by Native JavaScript. To create and work with modules in Javascript we require an external like CommonJS.18) Which object oriented terms are supported by TypeScript?TypeScript supports following object oriented terms.ModulesClassesInterfacesInheritanceData TypesMember functions19) How to Call Base Class Constructor from Child Class in TypeScript?super() function is used to called parent or base class constructor from Child Class.20) How do you implement inheritance in TypeScript?Inheritance is a mechanism that acquires the properties and behaviors of a class from another class. It is an important aspect of OOPs languages and has the ability which creates new classes from an existing class. The class whose members are inherited is called the base class, and the class that inherits those members is called the derived class.An Inheritance can be implemented by using the extend keyword. We can understand it by the following example.class Shape { Area:number constructor(area:number) { this.Area = area } } class Circle extends Shape { display():void { console.log("Area of the circle: "+this.Area) } } var obj = new Circle(320); obj.display() //Output: Area of the circle: 320 To know more click here.21) What are the Modules in Typescript?A module is a powerful way to create a group of related variables, functions, classes, and interfaces, etc. It can be executed within their own scope, not in the global scope. In other words, the variables, functions, classes, and interfaces declared in a module cannot be accessible outside the module directly.Creating a ModuleA module can be created by using the export keyword and can be used in other modules by using the import keyword.module module_name{ class xyz{ export sum(x, y){ return x+y; } } } To know more click here.22) What is the difference between the internal module and the external module?The difference between internal and external module is given below:SNInternal ModuleExternal Module1Internal modules were used to logically group the classes, interfaces, functions, variables into a single unit and can be exported in another module.External modules are useful in hiding the internal statements of the module definitions and show only the methods and parameters associated with the declared variable.2Internal modules were in the earlier version of Typescript. But they are still supported by using namespace in the latest version of TypeScript.External modules are simply known as a module in the latest version of TypeScript.3Internal modules are local or exported members of other modules (including the global module and external modules).External modules are separately loaded bodies of code referenced using external module names.4Internal modules are declared using ModuleDeclarations that specify their name and body.An external module is written as a separate source file that contains at least one import or export declaration.5Example:module Sum { export function add(a, b) { console.log("Sum: " +(a+b)); } } Example:export class Addition{ constructor(private x?: number, private y?: number){ } Sum(){ console.log("SUM: " +(this.x + this.y)); } }To know more in detail click here.23) What is namespace in Typescript? How to declare a namespace in Typescript?A namespace is a way that is used for logical grouping of functionalities. Namespaces are used to maintain the legacy code of typescript internally. It encapsulates the features and objects that share certain relationships. A namespace is also known as internal modules. A namespace can also include interfaces, classes, functions, and variables to support a group of related functionalities.Note: A namespace can be defined in multiple files and allow to keep each file as they were all defined in one place. It makes code easier to maintain.Synatax for creating namespacenamespace { export interface I1 { } export class c1{ } } To know more click here.24) Explain Decorators in Typescript?A Decorator is a special kind of declaration that can be applied to classes, methods, accessor, property, or parameter. Decorators are simply functions that are prefixed @expression symbol, where expression must evaluate to a function that will be called at runtime with information about the decorated declaration.TypeScript Decorators serves the purpose of adding both annotations and metadata to the existing code in a declarative way. Decorators are an experimental feature proposed for ES7. It is already in use by some of the JavaScript frameworks including Angular 2. The Decorators may change in future releases.To enable experimental support for decorators, we must enable the experimentalDecorators compiler option either on the command line or in our tsconfig.json:Command Line$tsc --target ES5 --experimentalDecorators tsconfig.json{ "compilerOptions": { "target": "ES5", "experimentalDecorators": true } } To know more click here.25) What are Mixins?In Javascript, Mixins are a way of building up classes from reusable components is to build them by combining simpler partial classes called mixins.The idea is simple, instead of a class A extending class B to get its functionality, function B takes class A and returns a new class with this added functionality. Function B is a mixin.26) What is default visibility for properties/methods in TypeScript classes?Public is the default visibility for properties/methods in TypeScript classes.27) How does TypeScript support optional parameters in function as in JavaScript every parameter is optional for a function?Unlike JavaScript, the TypeScript compiler will throw an error if we try to invoke a function without providing the exact number and types of parameters as declared in its function signature. To overcome this problem, we can use optional parameters by using question mark sign ('?'). It means that the parameters which may or may not receive a value can be appended with a '?' to mark them optional.function Demo(arg1: number, arg2? :number) { }So, arg1 is always required, and arg2 is an optional parameter. So, arg1 is always required, and arg2 is an optional parameter.Note: Optional parameters must follow the required parameters. If we want to make arg1 optional, instead of arg2, then we need to change the order and arg1 must be put after arg2.function Demo(arg2: number, arg1? :number) { } To know more click here.28) Does TypeScript supports function overloading as JavaScript doesn't support function overloading?Yes, TypeScript support function overloading. But the implementation is odd. When we perform function overloading in TypeScript, then we can implement only one functions with multiple signatures.//Function with string type parameter function add(a:string, b:string): string; //Function with number type parameter function add(a:number, b:number): number; //Function Definition function add(a: any, b:any): any { return a + b; } In the above example, the first two lines are the function overload declaration. It has two overloads. The first signature has a parameter of type string whereas the second signature has a parameter of type number. The third function contains the actual implementation and has a parameter of type any. Any data type can take any type of data. The implementation then checks for the type of the supplied parameter and execute a different piece of code based on supplier parameter type.29) Is it possible to debug any TypeScript file?Yes, it is possible. To debug any TypeScript file, we need .js source map file. So compile the .ts file with the --sourcemap flag to generate a source map file.$ tsc -sourcemap file1.ts This will create file1.js and file1.js.map. And last line of file1.js would be reference of source map file.//# sourceMappingURL=file1.js.map 30) What is TypeScript Definition Manager and why do we need it?TypeScript Definition Manager (TSD) is a package manager used to search and install TypeScript definition files directly from the community-driven DefinitelyTyped repository.Suppose, we want to use some jQuery code in our .ts file.$(document).ready(function() { //Your jQuery code }); Now, when we try to compile it by using tsc, it will give a compile-time error: Cannot find the name "$". So, we need to inform TypeScript compiler that "$" is belongs to jQuery. To do this, TSD comes into play. We can download jQuery Type Definition file and include it in our .ts file. Below are the steps to perform this:First, install TSD.$ npm install tsd -g In TypeScript directory, create a new TypeScript project by running:$ tsd init Then install the definition file for jQuery.tsd query jquery --action install The above command will download and create a new directory containing jQuery definition file ends with ".d.ts". Now, include definition file by updating TypeScript file to point to the jQuery definition./// $(document).ready(function() { //To Do }); Now, compile again. This time js file will be generated without any error. Hence, the need of TSD helps us to get type definition file for the required framework.31) What is TypeScript Declare Keyword?We know that all JavaScript libraries/frameworks don't have TypeScript declaration files, but we want to use them in our TypeScript file without any compilation errors. To do this, we use the declare keyword. The declare keyword is used for ambient declarations and methods where we want to define a variable that may exist elsewhere.For example, suppose we have a library called myLibrary that doesn't have a TypeScript declaration file and have a namespace called myLibrary in the global namespace. If we want to use that library in our TypeScript code, we can use the following code:declare var myLibrary; TypeScript runtime will assign the myLibrary variable as any type. Here is a problem that we won't get Intellisense in design time but we will be able to use the library in our code.32) How to generate TypeScript definition file from any .ts file?We can generate TypeScript definition file from any .ts file by using tsc compiler. It will be generating a TypeScript definition which makes our TypeScript file reusable.tsc --declaration file1.ts 33) What is tsconfig.json file?The tsconfig.json file is a file which is in JSON format. In the tsconfig.json file, we can specify various options to tell the compiler how to compile the current project. The presence of a tsconfig.json file in a directory indicates that the directory is the root of a TypeScript project. Below is a sample tsconfig.json file.{ "compilerOptions": { "declaration": true, "emitDecoratorMetadata": false, "experimentalDecorators": false, "module": "none", "moduleResolution": "node" "removeComments": true, "sourceMap": true }, "files": [ "main.ts", "othermodule.ts" ] } To know more click here.34) Explain generics in TypeScript?TypeScript Generics is a tool which provides a way to create reusable components. It is able to create components that can work with a variety of data types rather than a single data type. Generics provides type safety without compromising the performance, or productivity. Generics allow us to create generic classes, generic functions, generic methods, and generic interfaces.In generics, a type parameter is written between the open () brackets which makes it strongly typed collections. Generics use a special kind of type variable that denotes types. The generics collections contain only similar types of objects.function identity(arg: T): T { return arg; } let output1 = identity("myString"); let output2 = identity( 100 ); console.log(output1); console.log(output2); To know more click here.35) Does TypeScript support all object-oriented principles?Yes, TypeScript support all object-oriented principles. There are four main principles to object-oriented programming:Encapsulation,Inheritance,Abstraction, andPolymorphism.36) How to check null and undefined in TypeScript?By using a juggling-check, we can check both null and undefined:if (x == null) { } If we use a strict-check, it will always true for values set to null and won't evaluate as true for undefined variables.Examplevar a: number; var b: number = null; function check(x, name) { if (x == null) { console.log(name + ' == null'); } if (x === null) { console.log(name + ' === null'); } if (typeof x === 'undefined') { console.log(name + ' is undefined'); } } check(a, 'a'); check(b, 'b'); Output"a == null" "a is undefined" "b == null" "b === null" 37) Could we use TypeScript on the backend? If yes, how?Yes, we can use TypeScript on the backend. We can understand it with the following example. Here, we choose Node.js and have some additional type safety and the other abstraction that the language brings.Install Typescript compilernpm i -g typescript The TypeScript compiler takes options in the tsconfig.json file. This file determines where to put built files.{ "compilerOptions": { "target": "es5", "module": "commonjs", "declaration": true, "outDir": "build" } } Compile ts filestsc Runnode build/index.js 38) What is the difference between "interface vs type" statements?interface X { a: number b: string } type X = { a: number b: string }; SNinterfacetype1An interface declaration always introduces a named object type.A type alias declaration can introduce a name for any kind of type, including primitive, union, and intersection types.2An interface can be named in an extends or implements clause.Type alias for an object type literal cannot be named in an extends or implements clause.3Interfaces create a new name that is used everywhere.Type aliases don't create a new name.4An interface can have multiple merged declarations.Type alias for an object type literal cannot have multiple merged declarations.39) What are Ambients in TypeScripts and when to use them?Ambient declarations tell the compiler about the actual source code exist elsewhere. If these source codes do not exist at runtime and we try to use them, then it will break without warning.Ambient declarations files are like docs file. If the source changes, the docs need to be kept updated also. If the ambient declaration file is not updated, then we will get compiler errors.The Ambient declarations allow us to safely and easily use existing popular JavaScript libraries like jquery, angularjs, nodejs, etc.40) What is a TypeScript Map file?TypeScript Map file is a source map file which holds information about our original files..map files are source map files that let tools map between the emitted JavaScript code and the TypeScript source files that created it.Many debuggers can consume these files so we can debug the TypeScript file instead of the JavaScript file.41) What is Type assertions in TypeScript?Type assertion works like a typecasting in other languages, but it doesn't perform type checking or restructuring of data just like other languages can do like C# and Java. The typecasting comes with runtime support whereas type assertion has no impact on runtime. However, type assertions are used purely by the compiler and provide hints to the compiler on how we want our code to be analyzed.Examplelet empCode: any = 111; let employeeCode = code; console.log(typeof(employeeCode)); //Output: number To know more click here.42) What is "as" syntax in TypeScript?The as is the additional syntax for Type assertion in TypeScript. The reason for introducing the as-syntax is that the original syntax () conflicted with JSX.Examplelet empCode: any = 111; let employeeCode = code as number; When using TypeScript with JSX, only as-style assertions are allowed.43) What is JSX? Can we use JSX in TypeScript?JSX is NOTHING BUT Javascript with a different extension. Facebook came up with this new extension so that they can distinguish from the XML-like implementation of HTML in JavaScript.JSX is an embeddable XML-like syntax. It is meant to be transformed into valid JavaScript. JSX came to popularity with the React framework. TypeScript supports embedding, type checking, and compiling JSX directly into JavaScript.To use JSX, we must do two things.Name the files with a .tsx extensionEnable the jsx option44) What is Rest parameters?The rest parameter is used to pass zero or more values to a function. It is declared by prefixing the three dot characters ('...')before the parameter. It allows the functions to have a variable number of arguments without using the arguments object. It is very useful where we have an undetermined number of parameters.Rules to follow in rest parameter:Only one rest parameter is allowed in a function.It must be an array type.It must be a last parameter in the parameter list.function sum(a: number, ...b: number[]): number { let result = a; for (var i = 0; i
More detailsPublished - Tue, 06 Dec 2022
Created by - Admin s
A list of top frequently asked Blockchain Interview Questions and answers are given below.1) What is Blockchain?A Blockchain is a constantly growing ledger(file) that keeps a permanent record of all the transactions that have taken place, in a secure, chronological, and immutable way. It can be used for the secure transfer of money, property, contracts, etc. without requiring a third-party intermediary like bank or government.Blockchain is the backbone of the most famous cryptocurrency named Bitcoin. It is a peer to peer electronic cash system and a decentralized network which allows users to make transactions directly without the involvement of third-party to manage the exchange of funds.To know more Click Here...Play Videox2) What is the difference between Bitcoin blockchain and Ethereum blockchain?We can see the basic differences between Bitcoin blockchain and Ethereum blockchain in the below table.PointsBitcoin BlockchainEthereum BlockchainFounderSatoshi NakamotoVitalik ButerinRelease Date9 Jan 200830 July 2015Release MethodGenesis Block MinedPresaleUsageDigital CurrencySmart ContractsCryptocurrencyUsedBitcoin EtherAlgorithmSHA-256EthashBlocks Time10 minutes12-14 secondsScalableNot yetYes3) What are the different types of Blockchains?The different types of blockchains which introduce to the world are:There are mainly three types of Blockchains introduced to the world.1. Public BlockchainA Public blockchain is a kind of blockchain which is "for the people, by the people, and of the people." There is no in-charge it means anyone can read, write, and audit the blockchain. It is an open-source, distributed, and decentralizes public ledger so anyone can review anything on a public blockchain. They are considered to be Permissionless blockchain.2. Private BlockchainA Private blockchain is a private property of an individual or an organization. It is controlled by a single organization that determines who can read it, submit the transaction to it, and who can participate in the consensus process. They are considered to be permissioned blockchain.3. Consortium Blockchain or Federated BlockchainIn this blockchain, the consensus process is controlled by a pre-selected group, i.e., group of companies or representative individuals. These pre-selected group is coming together and making decisions for the best benefit of the whole network. Such groups are also called consortiums or a federation that's why the name consortium or federated blockchain.4) Where is a blockchain stored?The blockchain can be either stored as a flat file or as a database.5) What are the types of records that are present in the blockchain database?There are two types of records in a blockchain database.Transactional RecordsBlock RecordsBoth the records can easily be accessed and can integrate with each other without following any complex algorithm.6) List the key features of blockchain?The essential properties of a blockchain are:Decentralized SystemsDistributed ledgerSafer & Secure EcosystemFastLow Transaction FeesFault-TolerantMinting7) How does Blockchain differ from relational databases?The blockchain differs from the relational database in the following ways.PointsBlockchainRelational DatabaseUnit of dataBlockTableFailureNoneCan happenCentralized ControlNoYesModification in dataNot PossiblePossibleSingle Point of FailureDoes not existExists8) Name some popular platforms for developing blockchain applications.Some of the popular platforms for developing blockchain are:EthereumHyperledger SawtoothQuorumRippleR3 CordaQtumIOTAEOS9) What do you mean by blocks in the blockchain technology?A Blockchain consists of a list of records(some or all of the recent transaction). Such records are stored in blocks. Each time a block gets completed, a new block is generated. The block linked with other blocks constitutes a chain of blocks called Blockchain. Each block, after added into the blockchain, will be stored as a permanent database. We cannot delete or reverse any block from the blockchain.To know more Click Here...10) Every block of Blockchain consist of what elements?Every block must include these three things:A hash pointer to the previous blockTimestampList of transactions11) How does a block is recognized in the Blockchain approach?Each block in the blockchain consists of a hash value. The hash value acts as a link to the block which is before it, transaction data and in fact a stamp of time.12) How can blocks be identified?Blocks can be identified by their block height and block header hash.13) Can you modify the data in a block?No, it's not possible to modify the data in a block. In case any modification is required, you would have to erase the information from all other associated blocks too.14) Can you remove a complete block from a network?Yes, it is possible to remove a complete block from a network. There are times when only a specific portion of this online ledger is to be considered. There are default options and filters that can help us do this without making a lot of efforts.15) What type of records can be kept in the Blockchain? Is there any restriction on the same?No, it is not possible to give restriction for keeping records in the blockchain approach. We can put any type of data on a blockchain such as Bank records, health records, images, Facebook messages, etc.Some of the common types of records which can be kept in the blockchain are:Records of medical transactionsTransaction processingIdentity managementEvents related to organizations,Management activitiesDocumentation16) Which cryptographic algorithm is used in Blockchain?Blockchain uses SHA-256 Hashing algorithm. The National Security Agency (NSA) in the USA develop SHA-256 Hashing algorithm.To know more Click Here...17) In what order are the blocks linked in the blockchain?Blockchain always links each block in backward order. In other words, blockchain links each block with its previous block.18) What are the benefits of blockchain?Some of the important benefits of blockchain are:Settlement in real-time: In the financial industry, blockchain can allowing the quicker settlement of trades. It does not take a lengthy process for verification, settlement, and clearance because a single version of agreed-upon data is available between all stack holders.Cost-saving: Blockchain allows peer-to-peer transactions to be completed without the need for a third party such as a bank which reduced overhead costs for exchanging assets.Security and Resilience: Blockchain uses very advanced cryptography to make sure that the information which is going to lock inside the blockchain is secure against hacking attacks and fraud. It uses Distributed Ledger Technology where each party holds a copy of the original chain, so the system remains operative, even the large number of other nodes fall.Immutability: A blockchain register transactions in chronological order, which mean every transaction happens after the previous one. The chronological order certifies the unalterability of all operations in the blockchain. It means when a new block is added to the chain of ledgers, it cannot be removed or modified.User Pseudonymity: It is a state where the user has a consistent identifier which is not the real name of the user. The real identities are only available to administrators. It allows users to communicate with others in a generally anonymous way. It helps to maintain user privacy and enables free transactions without any security worries. In the blockchain, your pseudonym is the address to which you receive Bitcoin. Every transaction which involves that address is stored permanently in the blockchain. If your address is linked to your identity, every transaction will be linked to you. It is always good to every time use a new address for each transaction to avoid the transactions being linked to a common owner.19) What are the Merkle trees? What is its importance in blockchain?Merkle tree is a fundamental part of blockchain technology. It is a mathematical data structure composed of hashes of different blocks of data, and which serves as a summary of all the transactions in a block. It also allows for efficient and secure verification of content in a large body of data. It also helps to verify the consistency and content of the data. Both Bitcoin and Ethereum use Merkle Trees structure. Merkle Tree is also known as Hash Tree.The Merkle tree plays a vital role in blockchain technology. If someone needs to verify the existence of a specific transaction in a block, then there is no need to download the entire block to verify the transaction in a block. He can only download the chain of block headers. It allows downloading a collection of a branch of the tree which contains this transaction is enough. We check the hashes which are relevant to your transactions. If these hashes check out is correct, then we know that this particular transaction exists in this block.To know more Click Here...20) What is Double Spending? Is it possible to double spend in a Blockchain system?Double spending means spending the same money multiple times. In a physical currency, the double-spending problem can never arise. But in digital cash-like bitcoin, the double-spending problem can arise. Hence, in Bitcoin transactions, there is a possibility of being copied and rebroadcasted. It makes it possible that the same bitcoin could be spent twice by its owner. One of the primary aims of Blockchain technology is to eliminate this approach up to the possible extent.Blockchain prevents the double-spending problem by implementing a confirmation mechanism from multiple parties before the actual transaction added to the ledger.To know more Click Here...21) What is a ledger? Name the common type of ledgers that can be considered by users in Blockchain?A ledger is a file that is constantly growing. It keeps a permanent record of all the transactions that have taken place between two parties on the blockchain network.There are three common types of a ledger that can be considered by users in the blockchain:Centralized NetworkDecentralized NetworkDistributed Network22) Why is Blockchain a trusted approach?Blockchain is a trusted approach due to the following reasons:It is easily compatible with other business applications due to its open-source nature.It is safe, hacking proof and encrypted.There is no central authority to control it.All participants agreed to how a transaction inserted into the blockchain.The transaction is immutable means once the transaction inserted into the blockchain, we cannot change it.23) What is mean by DAO?The DAO stands for Decentralized Autonomous Organization. It is an organization that is both autonomous and decentralized. It is represented by rules encoded as a computer program that is transparent, controlled by shareholders, and not influenced by the central government.A DAO can be seen as the most complex form of a smart contract. A smart contract is a computer program that autonomously exists on the Internet, but at the same time, it needs people to perform a task that it can't do by itself.A DAO's financial transaction record and program rules are maintained on a blockchain. Since DAO runs on a blockchain, and it's running on a distributed network, you can have multiple combinations of different parties exchanging value and reaching agreements. It means that, to a Decentralized Autonomous Organization, it doesn't matter if you are a human being or you're a robot. You can actually have devices communicating with devices, or devices communicating with people, or people communicating with people. To DAO, it makes no difference because as long as it's programmed into the collection of smart contracts, the whole thing can run automatically and immutable.To know more Click Here...24) What do you mean by Coinbase transaction?A Coinbase transaction is the first transaction in a block. It is a unique type of bitcoin transaction that can be created by a miner. The miners use it to collect the block reward for their work and any other transaction fees collected by the miner are also sent in this transaction.To know more Click Here...25) What is the difference between blockchain and database?The important differences between the blockchain and database are:SNBlockchainDatabase1.Blockchain is Decentralized. Here, no one is an administrator means everyone is an in-charge.The database is centralized. It has administrators who control all the data.2.Everyone has rights to read and write.Only authorized people can read and write.3.Peer-to-peer architecture.Client-server architecture.4.Here, only Append operation is allowed.CRUD(Create, Read, Update, Delete) mechanism is possible.5.Historical data of digital records.No records of ownership.6.Blockchains are fully confidential.Databases are not fully confidential.7.Blockchain is slow because it depends on the hash rate.The database is fast because fewer people administer it.8.Blockchain is permissionless.The database is permissioned.To know more Click Here...26) What is Cryptocurrency?Cryptocurrency is a digital asset(currencies) which can be used to exchange value between parties. It uses strong cryptography to secure and verify the financial transactions as well as control the creation of new units of that currency. As we know, it is a digital currency, so it doesn't exist physically. Some popular cryptocurrencies are Bitcoin, Litecoin, Z-Cash, Monero, Dash, etc.We know that the government prints the government currencies like fiat currency such as Dollar, Rupees, Yen or Yuan itself. It means there is a centralized institution exists which can create thousands or millions or billions more of that currency. Unlike government currencies like bitcoin, these type of currencies is created by the same mathematical formulas that make the cryptocurrency work. Thus, cryptocurrencies use decentralized control, which works through distributed ledger technology that serves as a public financial transaction database.To know more Click Here...27) What are the limitations of blockchain?The major limitations of blockchain are:Lack of Technical TalentToday, there are a lot of developers available who can do a lot of different things in every field. But in the blockchain technology, there are not so many developers available who have specialized expertise in blockchain technology. Hence, the lack of developers is a hindrance to developing anything on the blockchain.Network SizeBlockchains require a vast network of users. Therefore it is not much resistant to the wrong action as well as it responds to attacks and grows stronger. The blockchain is a robust network with a widely distributed grid of nodes, which makes it more difficult to reap the full benefit.Security FlawBitcoin and other blockchains are associated with one considerable security flaw known as a "51% attack." This security flaw refers to a situation when a group of "miners" takes control of more than half of the blockchain network's computing power. If the miners somehow acquire sufficient computational power, then there is no centralized authority to prevent them from influencing the entire Bitcoin network. It means the attacker can block new transactions from taking place or being confirmed. They are also able to reverse the transactions that have already validated during that same period. Due to this, they could spend coins twice.For this reason, Bitcoin mining pools are closely monitored by the community who ensure that no one gains such network influence.Speed and cost of transactionsThe first few years of the existence of blockchain, transactions cost are "nearly free." But as the network grows, it will NOT be the most cost-effective option of transferring money due to rising transaction costs in the network. From the end of 2016, it processes only seven transactions per second, and each transaction costs around 0.20$.Consensus MechanismIn the blockchain, we know that a block can be created in every 10 minutes. It is because every transaction made must ensure that every block in the blockchain network must reach a common consensus. Depending on the network size and the number of blocks or nodes involved in a blockchain, the back-and-forth communications involved to attain a consensus can consume a considerable amount of time and resources.To know more Click Here...28) What is a 51% attack?The 51% attack on a blockchain network refers to a miner or a group of miners who are trying to control more than 50% of a network's mining power, computing power or hash rate. In this attack, the attacker can block new transactions from taking place or being confirmed. They are also able to reverse transactions that have already confirmed while they were in control of the network, leading to a double-spending problem.To know more Click Here...29) What is encryption? What is its role in Blockchain?We know that the security of data is always matters. Encryption is a process of converting information or data into a code to prevent unauthorized access. It helps organizations to keep their data secure(i.e., prevent unauthorized access). In this technique, the data is encoded or changed into an unreadable format up to some extent before it is sent out of a network by the sender. The only receiver can understand how to decode the same.In Blockchain technology, this approach is very useful because it makes the overall security and authenticity of blocks and help to keep them secure.30) What is the difference between Proof-of-work and Proof-of-stake?The main differences between the Proof of Work and Proof of Stake are:Proof of WorkProof of Work(PoW) algorithm is used to confirm the transaction and creates a new block to the chain. In this algorithm, miners compete against each other to complete the transaction on the network. The process of competing against each other is called mining. It defines an expensive computer calculation. In this, a reward is given to the first miner who solves each blocks problem.Proof of StakeIn the case of PoS algorithm, a set of nodes decide to stake their own cryptocurrencies for the transaction validation. They are called 'stakers.' In proof of stake, the creator of a new block is chosen in a deterministic way, depending on its wealth, also defined as stake. It does not give any block reward, so miners take the transaction fees only. Proof-of-Stake can be several thousand times more cost-effective as compared to proof of work.31) How does the security of a block works?A blockchain is a chain of blocks that contain records of transactions. Block is the most secure part of a blockchain. The record of a blockchain is protected through a cryptographic hash algorithm. Each block is connected with all other blocks before and after it through a distinctive hash pointer which adds more security to the block. If the value within a block is modified, the hash value will also change. This hash is a security identifier which provides a reasonable level of security to the whole blockchain.Ambitious hackers also need to know the hash key of the previous block to make changes to the block information. For those ambitious hackers, blockchains are decentralized and distributed across peer-to-peer networks that are continuously updated and keep syncing. Since these records are not contained in a central location, so blockchains don't have a single point of failure and cannot be changed from a single computer.32) What is the difference between public and private key?The private key is used to encrypt or lock a message or transaction which is sent on the blockchain network. The sender can send a message using the public key of the receiver. On the other hand, the receiver can decrypt the message or the transaction using his private key. By using the private and public key, the communication or transaction is kept safe and tamper-proof.33) Name the platforms that are actively developing Blockchain applications?Blockchain technology was first used for financial transactions. But nowadays, its scope is increasing and applies in a variety of industries like e-commerce, data management, energy, gaming, e-governance, and many more. There are several commercial and open-source platforms available to provide the framework for creating applications that support a blockchain. Hyperledger and Ethereum are actively improving the blockchain ecosystem by creating advanced cross-industry blockchain technologies.Hyperledger is an open-source collaboration that provides tools and techniques for developing an enterprise-grade blockchain solution. While Ethereum is an open-source and leading platform designed for developers, organizations, and business to build and deploy blockchain applications.34) How does bitcoin use blockchain?A transaction is a transfer of value between Bitcoin wallets that gets included in the blockchain. Bitcoin wallets keep a secret piece of data called a private key. The private key is used to sign transactions and provide mathematical proof that they have come from the owner of the wallet.35) What is Consensus algorithm?The consensus algorithm is the method of gaining consensus on a change of data over the system or distributed network. Consensus algorithms are heavily used in blockchains as they enable the network of unknown nodes to reach consensus on the data that is being stored or shared through the blockchain.36) What are the types of consensus algorithms?There are many types of consensus algorithms or techniques available. The most popular consensus algorithm is:Proof-of-Work(PoW)Proof-of-Stake(PoS)Delegated Proof-of-Stake(DPoS)Proof-of-Authority(PoA)Proof-of-Elapsed Time(PoET)Byzantine Fault Tolerance
More detailsPublished - Tue, 06 Dec 2022
Created by - Admin s
A list of top frequently asked Blockchain Interview Questions and answers are given below.1) What is Blockchain?A Blockchain is a constantly growing ledger(file) that keeps a permanent record of all the transactions that have taken place, in a secure, chronological, and immutable way. It can be used for the secure transfer of money, property, contracts, etc. without requiring a third-party intermediary like bank or government.Blockchain is the backbone of the most famous cryptocurrency named Bitcoin. It is a peer to peer electronic cash system and a decentralized network which allows users to make transactions directly without the involvement of third-party to manage the exchange of funds.To know more Click Here...Play Videox2) What is the difference between Bitcoin blockchain and Ethereum blockchain?We can see the basic differences between Bitcoin blockchain and Ethereum blockchain in the below table.PointsBitcoin BlockchainEthereum BlockchainFounderSatoshi NakamotoVitalik ButerinRelease Date9 Jan 200830 July 2015Release MethodGenesis Block MinedPresaleUsageDigital CurrencySmart ContractsCryptocurrencyUsedBitcoin EtherAlgorithmSHA-256EthashBlocks Time10 minutes12-14 secondsScalableNot yetYes3) What are the different types of Blockchains?The different types of blockchains which introduce to the world are:There are mainly three types of Blockchains introduced to the world.1. Public BlockchainA Public blockchain is a kind of blockchain which is "for the people, by the people, and of the people." There is no in-charge it means anyone can read, write, and audit the blockchain. It is an open-source, distributed, and decentralizes public ledger so anyone can review anything on a public blockchain. They are considered to be Permissionless blockchain.2. Private BlockchainA Private blockchain is a private property of an individual or an organization. It is controlled by a single organization that determines who can read it, submit the transaction to it, and who can participate in the consensus process. They are considered to be permissioned blockchain.3. Consortium Blockchain or Federated BlockchainIn this blockchain, the consensus process is controlled by a pre-selected group, i.e., group of companies or representative individuals. These pre-selected group is coming together and making decisions for the best benefit of the whole network. Such groups are also called consortiums or a federation that's why the name consortium or federated blockchain.4) Where is a blockchain stored?The blockchain can be either stored as a flat file or as a database.5) What are the types of records that are present in the blockchain database?There are two types of records in a blockchain database.Transactional RecordsBlock RecordsBoth the records can easily be accessed and can integrate with each other without following any complex algorithm.6) List the key features of blockchain?The essential properties of a blockchain are:Decentralized SystemsDistributed ledgerSafer & Secure EcosystemFastLow Transaction FeesFault-TolerantMinting7) How does Blockchain differ from relational databases?The blockchain differs from the relational database in the following ways.PointsBlockchainRelational DatabaseUnit of dataBlockTableFailureNoneCan happenCentralized ControlNoYesModification in dataNot PossiblePossibleSingle Point of FailureDoes not existExists8) Name some popular platforms for developing blockchain applications.Some of the popular platforms for developing blockchain are:EthereumHyperledger SawtoothQuorumRippleR3 CordaQtumIOTAEOS9) What do you mean by blocks in the blockchain technology?A Blockchain consists of a list of records(some or all of the recent transaction). Such records are stored in blocks. Each time a block gets completed, a new block is generated. The block linked with other blocks constitutes a chain of blocks called Blockchain. Each block, after added into the blockchain, will be stored as a permanent database. We cannot delete or reverse any block from the blockchain.To know more Click Here...10) Every block of Blockchain consist of what elements?Every block must include these three things:A hash pointer to the previous blockTimestampList of transactions11) How does a block is recognized in the Blockchain approach?Each block in the blockchain consists of a hash value. The hash value acts as a link to the block which is before it, transaction data and in fact a stamp of time.12) How can blocks be identified?Blocks can be identified by their block height and block header hash.13) Can you modify the data in a block?No, it's not possible to modify the data in a block. In case any modification is required, you would have to erase the information from all other associated blocks too.14) Can you remove a complete block from a network?Yes, it is possible to remove a complete block from a network. There are times when only a specific portion of this online ledger is to be considered. There are default options and filters that can help us do this without making a lot of efforts.15) What type of records can be kept in the Blockchain? Is there any restriction on the same?No, it is not possible to give restriction for keeping records in the blockchain approach. We can put any type of data on a blockchain such as Bank records, health records, images, Facebook messages, etc.Some of the common types of records which can be kept in the blockchain are:Records of medical transactionsTransaction processingIdentity managementEvents related to organizations,Management activitiesDocumentation16) Which cryptographic algorithm is used in Blockchain?Blockchain uses SHA-256 Hashing algorithm. The National Security Agency (NSA) in the USA develop SHA-256 Hashing algorithm.To know more Click Here...17) In what order are the blocks linked in the blockchain?Blockchain always links each block in backward order. In other words, blockchain links each block with its previous block.18) What are the benefits of blockchain?Some of the important benefits of blockchain are:Settlement in real-time: In the financial industry, blockchain can allowing the quicker settlement of trades. It does not take a lengthy process for verification, settlement, and clearance because a single version of agreed-upon data is available between all stack holders.Cost-saving: Blockchain allows peer-to-peer transactions to be completed without the need for a third party such as a bank which reduced overhead costs for exchanging assets.Security and Resilience: Blockchain uses very advanced cryptography to make sure that the information which is going to lock inside the blockchain is secure against hacking attacks and fraud. It uses Distributed Ledger Technology where each party holds a copy of the original chain, so the system remains operative, even the large number of other nodes fall.Immutability: A blockchain register transactions in chronological order, which mean every transaction happens after the previous one. The chronological order certifies the unalterability of all operations in the blockchain. It means when a new block is added to the chain of ledgers, it cannot be removed or modified.User Pseudonymity: It is a state where the user has a consistent identifier which is not the real name of the user. The real identities are only available to administrators. It allows users to communicate with others in a generally anonymous way. It helps to maintain user privacy and enables free transactions without any security worries. In the blockchain, your pseudonym is the address to which you receive Bitcoin. Every transaction which involves that address is stored permanently in the blockchain. If your address is linked to your identity, every transaction will be linked to you. It is always good to every time use a new address for each transaction to avoid the transactions being linked to a common owner.19) What are the Merkle trees? What is its importance in blockchain?Merkle tree is a fundamental part of blockchain technology. It is a mathematical data structure composed of hashes of different blocks of data, and which serves as a summary of all the transactions in a block. It also allows for efficient and secure verification of content in a large body of data. It also helps to verify the consistency and content of the data. Both Bitcoin and Ethereum use Merkle Trees structure. Merkle Tree is also known as Hash Tree.The Merkle tree plays a vital role in blockchain technology. If someone needs to verify the existence of a specific transaction in a block, then there is no need to download the entire block to verify the transaction in a block. He can only download the chain of block headers. It allows downloading a collection of a branch of the tree which contains this transaction is enough. We check the hashes which are relevant to your transactions. If these hashes check out is correct, then we know that this particular transaction exists in this block.To know more Click Here...20) What is Double Spending? Is it possible to double spend in a Blockchain system?Double spending means spending the same money multiple times. In a physical currency, the double-spending problem can never arise. But in digital cash-like bitcoin, the double-spending problem can arise. Hence, in Bitcoin transactions, there is a possibility of being copied and rebroadcasted. It makes it possible that the same bitcoin could be spent twice by its owner. One of the primary aims of Blockchain technology is to eliminate this approach up to the possible extent.Blockchain prevents the double-spending problem by implementing a confirmation mechanism from multiple parties before the actual transaction added to the ledger.To know more Click Here...21) What is a ledger? Name the common type of ledgers that can be considered by users in Blockchain?A ledger is a file that is constantly growing. It keeps a permanent record of all the transactions that have taken place between two parties on the blockchain network.There are three common types of a ledger that can be considered by users in the blockchain:Centralized NetworkDecentralized NetworkDistributed Network22) Why is Blockchain a trusted approach?Blockchain is a trusted approach due to the following reasons:It is easily compatible with other business applications due to its open-source nature.It is safe, hacking proof and encrypted.There is no central authority to control it.All participants agreed to how a transaction inserted into the blockchain.The transaction is immutable means once the transaction inserted into the blockchain, we cannot change it.23) What is mean by DAO?The DAO stands for Decentralized Autonomous Organization. It is an organization that is both autonomous and decentralized. It is represented by rules encoded as a computer program that is transparent, controlled by shareholders, and not influenced by the central government.A DAO can be seen as the most complex form of a smart contract. A smart contract is a computer program that autonomously exists on the Internet, but at the same time, it needs people to perform a task that it can't do by itself.A DAO's financial transaction record and program rules are maintained on a blockchain. Since DAO runs on a blockchain, and it's running on a distributed network, you can have multiple combinations of different parties exchanging value and reaching agreements. It means that, to a Decentralized Autonomous Organization, it doesn't matter if you are a human being or you're a robot. You can actually have devices communicating with devices, or devices communicating with people, or people communicating with people. To DAO, it makes no difference because as long as it's programmed into the collection of smart contracts, the whole thing can run automatically and immutable.To know more Click Here...24) What do you mean by Coinbase transaction?A Coinbase transaction is the first transaction in a block. It is a unique type of bitcoin transaction that can be created by a miner. The miners use it to collect the block reward for their work and any other transaction fees collected by the miner are also sent in this transaction.To know more Click Here...25) What is the difference between blockchain and database?The important differences between the blockchain and database are:SNBlockchainDatabase1.Blockchain is Decentralized. Here, no one is an administrator means everyone is an in-charge.The database is centralized. It has administrators who control all the data.2.Everyone has rights to read and write.Only authorized people can read and write.3.Peer-to-peer architecture.Client-server architecture.4.Here, only Append operation is allowed.CRUD(Create, Read, Update, Delete) mechanism is possible.5.Historical data of digital records.No records of ownership.6.Blockchains are fully confidential.Databases are not fully confidential.7.Blockchain is slow because it depends on the hash rate.The database is fast because fewer people administer it.8.Blockchain is permissionless.The database is permissioned.To know more Click Here...26) What is Cryptocurrency?Cryptocurrency is a digital asset(currencies) which can be used to exchange value between parties. It uses strong cryptography to secure and verify the financial transactions as well as control the creation of new units of that currency. As we know, it is a digital currency, so it doesn't exist physically. Some popular cryptocurrencies are Bitcoin, Litecoin, Z-Cash, Monero, Dash, etc.We know that the government prints the government currencies like fiat currency such as Dollar, Rupees, Yen or Yuan itself. It means there is a centralized institution exists which can create thousands or millions or billions more of that currency. Unlike government currencies like bitcoin, these type of currencies is created by the same mathematical formulas that make the cryptocurrency work. Thus, cryptocurrencies use decentralized control, which works through distributed ledger technology that serves as a public financial transaction database.To know more Click Here...27) What are the limitations of blockchain?The major limitations of blockchain are:Lack of Technical TalentToday, there are a lot of developers available who can do a lot of different things in every field. But in the blockchain technology, there are not so many developers available who have specialized expertise in blockchain technology. Hence, the lack of developers is a hindrance to developing anything on the blockchain.Network SizeBlockchains require a vast network of users. Therefore it is not much resistant to the wrong action as well as it responds to attacks and grows stronger. The blockchain is a robust network with a widely distributed grid of nodes, which makes it more difficult to reap the full benefit.Security FlawBitcoin and other blockchains are associated with one considerable security flaw known as a "51% attack." This security flaw refers to a situation when a group of "miners" takes control of more than half of the blockchain network's computing power. If the miners somehow acquire sufficient computational power, then there is no centralized authority to prevent them from influencing the entire Bitcoin network. It means the attacker can block new transactions from taking place or being confirmed. They are also able to reverse the transactions that have already validated during that same period. Due to this, they could spend coins twice.For this reason, Bitcoin mining pools are closely monitored by the community who ensure that no one gains such network influence.Speed and cost of transactionsThe first few years of the existence of blockchain, transactions cost are "nearly free." But as the network grows, it will NOT be the most cost-effective option of transferring money due to rising transaction costs in the network. From the end of 2016, it processes only seven transactions per second, and each transaction costs around 0.20$.Consensus MechanismIn the blockchain, we know that a block can be created in every 10 minutes. It is because every transaction made must ensure that every block in the blockchain network must reach a common consensus. Depending on the network size and the number of blocks or nodes involved in a blockchain, the back-and-forth communications involved to attain a consensus can consume a considerable amount of time and resources.To know more Click Here...28) What is a 51% attack?The 51% attack on a blockchain network refers to a miner or a group of miners who are trying to control more than 50% of a network's mining power, computing power or hash rate. In this attack, the attacker can block new transactions from taking place or being confirmed. They are also able to reverse transactions that have already confirmed while they were in control of the network, leading to a double-spending problem.To know more Click Here...29) What is encryption? What is its role in Blockchain?We know that the security of data is always matters. Encryption is a process of converting information or data into a code to prevent unauthorized access. It helps organizations to keep their data secure(i.e., prevent unauthorized access). In this technique, the data is encoded or changed into an unreadable format up to some extent before it is sent out of a network by the sender. The only receiver can understand how to decode the same.In Blockchain technology, this approach is very useful because it makes the overall security and authenticity of blocks and help to keep them secure.30) What is the difference between Proof-of-work and Proof-of-stake?The main differences between the Proof of Work and Proof of Stake are:Proof of WorkProof of Work(PoW) algorithm is used to confirm the transaction and creates a new block to the chain. In this algorithm, miners compete against each other to complete the transaction on the network. The process of competing against each other is called mining. It defines an expensive computer calculation. In this, a reward is given to the first miner who solves each blocks problem.Proof of StakeIn the case of PoS algorithm, a set of nodes decide to stake their own cryptocurrencies for the transaction validation. They are called 'stakers.' In proof of stake, the creator of a new block is chosen in a deterministic way, depending on its wealth, also defined as stake. It does not give any block reward, so miners take the transaction fees only. Proof-of-Stake can be several thousand times more cost-effective as compared to proof of work.31) How does the security of a block works?A blockchain is a chain of blocks that contain records of transactions. Block is the most secure part of a blockchain. The record of a blockchain is protected through a cryptographic hash algorithm. Each block is connected with all other blocks before and after it through a distinctive hash pointer which adds more security to the block. If the value within a block is modified, the hash value will also change. This hash is a security identifier which provides a reasonable level of security to the whole blockchain.Ambitious hackers also need to know the hash key of the previous block to make changes to the block information. For those ambitious hackers, blockchains are decentralized and distributed across peer-to-peer networks that are continuously updated and keep syncing. Since these records are not contained in a central location, so blockchains don't have a single point of failure and cannot be changed from a single computer.32) What is the difference between public and private key?The private key is used to encrypt or lock a message or transaction which is sent on the blockchain network. The sender can send a message using the public key of the receiver. On the other hand, the receiver can decrypt the message or the transaction using his private key. By using the private and public key, the communication or transaction is kept safe and tamper-proof.33) Name the platforms that are actively developing Blockchain applications?Blockchain technology was first used for financial transactions. But nowadays, its scope is increasing and applies in a variety of industries like e-commerce, data management, energy, gaming, e-governance, and many more. There are several commercial and open-source platforms available to provide the framework for creating applications that support a blockchain. Hyperledger and Ethereum are actively improving the blockchain ecosystem by creating advanced cross-industry blockchain technologies.Hyperledger is an open-source collaboration that provides tools and techniques for developing an enterprise-grade blockchain solution. While Ethereum is an open-source and leading platform designed for developers, organizations, and business to build and deploy blockchain applications.34) How does bitcoin use blockchain?A transaction is a transfer of value between Bitcoin wallets that gets included in the blockchain. Bitcoin wallets keep a secret piece of data called a private key. The private key is used to sign transactions and provide mathematical proof that they have come from the owner of the wallet.35) What is Consensus algorithm?The consensus algorithm is the method of gaining consensus on a change of data over the system or distributed network. Consensus algorithms are heavily used in blockchains as they enable the network of unknown nodes to reach consensus on the data that is being stored or shared through the blockchain.36) What are the types of consensus algorithms?There are many types of consensus algorithms or techniques available. The most popular consensus algorithm is:Proof-of-Work(PoW)Proof-of-Stake(PoS)Delegated Proof-of-Stake(DPoS)Proof-of-Authority(PoA)Proof-of-Elapsed Time(PoET)Byzantine Fault Tolerance
More detailsPublished - Tue, 06 Dec 2022
Created by - Admin s
A list of top frequently asked Bitcoin Interview Questions and answers are given below.1) What is Bitcoin?A bitcoin is a type of digital currency which can be bought, sold, and transfer between the two parties securely over the internet. It cannot be touched and seen, but it can be traded electronically. We can store it in our mobiles, computers or any other storage media as a virtual currency. Bitcoin can store values much like fine gold, silver, and some other type of investments. It can be used to buy products and services as well as make payments and exchange values electronically. It is the most popular cryptocurrency in the world.To read more information, Click Here...2) What do you mean by Bitcoin Mining?Bitcoin mining is performed by bitcoin miners(a group of people). The procedure of bitcoin mining is done by specialized computers equipped for solving algorithmic equations. Miners achieve bitcoin mining by solving a computational problem which makes the chain of blocks of transactions. These specialized computers help miners to authenticate the block of transaction held within each bitcoin network. Whenever a new block added into the blockchain, immediately miners get rewards for this new block. The miners get rewards in bitcoin along with transaction fees.Play Videox3) Who developed Bitcoin?Bitcoin was invented by an unknown person Satoshi Nakamoto in the year 2008. But there is no valid proof for this because the person behind bitcoin has never given an interview. It was released as open-source software in 2009. It was the first successful virtual currency designed with faith and equivalent to authorized currency of centralized government. It is a digital currency that uses rules of cryptography for regulation and generation of units of currency. It is commonly called decentralized digital currency.To read more information, Click Here...4) Who governs Bitcoin?Bitcoin is not a company, so no one can govern the Bitcoin. Bitcoin is decentralized digital money that is issued and managed without any centralized authority. It is created as a reward in a competition in which miners who own the specialized computer offer their computing power to verify and generate new Bitcoins. They are also responsible for maintaining the security of the network into the blockchain. The activity of creating a bitcoin is known as mining, and every successful miner gets a reward with newly created bitcoins and transaction fees.5) What is a Bitcoin wallet?A Bitcoin wallet(digital wallet) is a software program where Bitcoins are stored. Technically, a Bitcoin wallet is stored a private key(secret number) for every Bitcoin address. The owner of the wallet can send, receive, and exchange bitcoins. The Bitcoin wallet is of many forms, and some of them are a desktop wallet, mobile wallet, web wallet, and hardware wallet.To read more information, Click Here...6) How can you choose a Bitcoin wallet?Choosing the best bitcoin wallet is the most important step in becoming a Bitcoin user. There are two initial steps to finding a Bitcoin wallet given below:Decide what sort of crypto wallet you needConsider specific wallets to find the best one for you.Bitcoin wallets differ in many ways, such as security, convenience, level of privacy, coin support, and anonymity, customer support, user interface, fees, built-in services, and other variables.The most common distinction in choosing Bitcoin wallets is whether they are a cold wallet or hot wallet.Cold: The cold wallets refer to offline storage of bitcoins. These type of wallets are less convenient for frequent use, but they are more secure.Hot: The hot wallets are connected to the internet most of the time. These type of wallets are suitable for daily use, but they are not secure.Here, I will take an example of a page called bitcoin.org to choose a wallet. Bitcoin.org is a very good starting point to explain how to choose your wallet because there is a lot of options available. In this page, we will go to an option called Choose your wallet and decides the wallet type which you wants. These wallets are a desktop wallet, mobile wallet, web wallet, and hardware wallet.To read more information, Click Here...7) What is a Bitcoin address?A bitcoin address is a unique identifier which consists of 26-35 alphanumeric characters. The identifier begins with the number 1 or 3, which represents a location where the cryptocurrencies can be sent. The bitcoin user can generate a bitcoin address without any cost. However, the bitcoin address is not permanent, that means it may change for every new transaction.There are currently three standard address formats in use:P2PKH: It always begins with the number 1, e.g., 1BvBMSEYvtWesqTFn5Au4n4GFg7xJaNVN2.P2SH: It always begins with the number 3, e.g., 3J78t1WpEZ72CMnQviedrnyiWrnqRhWMLy.Bech32: It always begins with bc1, e.g., bc1qat0srrr7xdkvy5l643lxcnw9re59gtzxwf5ndq.8) Is Bitcoin Anonymous?No, bitcoin is not completely anonymous; instead, it is pseudonymous, i.e. every identity is tied with the fake name. It is because each user has a public address, and whenever there are financial transactions occur, the fraudsters will survive to trace that addresses.9) Who sets the Bitcoin price?The price of bitcoin is determined by the market in which it trades. It is determined by how much someone is willing to pay for that bitcoin. The market sets the price of bitcoin as same as Gold, Oil, Sugar, Grains, etc. is determined. Bitcoin, like any other market, is subject to the rules of supply and demand. i.e.,More Demand, Less Supply = Price Goes Up More Supply, Less Demand = Price Goes Down No one, in particular, sets the bitcoin's price nor we can trade it in one place. Each market/exchange determines its price based on supply and demand.To read more information, Click Here...10) Why are Bitcoin prices fluctuating?The price of bitcoin is fluctuating because it is very volatile in nature. Since the number of bitcoins is limited in circulation, new bitcoins are created at a decreasing rate. It means that demand must follow this level of inflation to keep the price stable. The bitcoin market is still relatively small as compared to other industries. Therefore it does not take significant amounts of money to move the market price up or down.To read more information, Click Here...11) How is Bitcoin purchased?We can purchase the bitcoin from many sources. Some of them are given below.It can be purchased from online with the help of credit cards or other e-wallets like PayPal etc.It can also be purchased with the help of LocalBitcoins and from Bitcoin Teller Machines, which is equivalent to Cash vending ATMs.Bitcoin.com provides a list of authenticated online exchanges centres where you can sell and purchase Bitcoins.12) How can you sell Bitcoins?We can sell Bitcoins in many ways. We can sell it online to an exchange or some other people who live nearby. It can be sold in the same way as it can be purchased. The price of bitcoin fluctuates regularly as per the demand and supply. It can also be sold through bitcoin ATMs, which allow selling and buying of Bitcoins. The transaction fees of bitcoin are the lowest amongst all bank charges applied globally.13) Can stores accept Bitcoins?As we know, anyone can accept Bitcoin. Many B2B services and hardware installation are available for the convenience of the storeowners. All these business organizations give invoicing and accounting with their services. All third party services are not compulsory. Individuals can also transact and invoice on their own.14) How can you convert Bitcoin into Fiat currencies?It is very important to know how to cash out bitcoin or withdraw from bitcoins into fiat currency (USD, EUR, INR), which will be acceptable in their native countries. There are some easy ways listed below which convert BTC into USD, INR, EUR or GBP. Before picking any of the listed methods, you need to find out how you want to receive your fiat currency. You can sell Bitcoins in person for cash or can sell it on exchanges and get the money directly into your bank account.Cryptocurrency ExchangeBitcoin Debit cardSelling bitcoinsBitcoin ATMsTo read more information, Click Here...15) Can I mine Bitcoins?Bitcoin mining is not an easy process. It requires specialized computers which can perform the calculation of large mathematical algorithm. These specialized computers are very costly, and power consumption has gone extremely high. For installation of one such computer or machine, you have to check for a cost-effective environment which is not easy these days. Today, Bitcoin mining machines are constantly being upgraded, and the moment becomes obsolete. Therefore, it will be very difficult to mine any more Bitcoin.16) Can I trade bitcoin without selling at an exchange?Yes, it is possible to trade bitcoins directly without selling at an exchange. Many people prefer this because of their security and trust. Many exchanges were hacked in recent time, and the result of this, their bitcoins vanished without any explanation.Another reason is its privacy. These days exchanges have similar KYC requirements as like banks needs. The KYC information is at risk of theft if the security of the exchange up to date.17) What can I buy with Bitcoins?We can purchase anything with bitcoins that are legally sold in the world like clothing, electronics, food and art to handmade crafts. Bitcoin can also be used to buy large items like cars, real estate, and investment vehicles such as precious metals. If you buy anything from Amazon through bitcoin, you can get up to 20% discount. Some others also give a discount to people who pay with the digital currency. Bitcoin has its own stores where you can buy T-shirts, bag, hoodie, accessories, etc.18) Is Bitcoin legal?Bitcoin is legal in many countries in the world, but some countries state that they have banned its use, such as India, China, and Ecuador. The cryptocurrencies regulations can vary from country to country so you should have to do a proper search before the initiation of bitcoin transaction in any organization. Wikipedia and many other online services have a great guide on how Bitcoin is treated in all the countries around the world with its regulatory policies.19) How does Bitcoin work?Each Bitcoin is a computer file which is stored as a digital wallet in smartphones or computer and functions similar to any e-wallet app. Bitcoins use his currency in a digitalized form which has its limits of production and limited to 21 million Bitcoins only. You can send Bitcoins to your digital wallet and then can send Bitcoins to other people. Every single bitcoin transaction is recorded in a public ledger called the blockchain. The blockchain makes it possible to trace the history of Bitcoins to stop people from spending bitcoins they do not own. It also restricts to make copies or undoing transactions.20) What are the advantages of bitcoin?Following are the benefits of Bitcoins:It is accepted worldwide at the same rates, and there is no risk of depreciation or appreciation.It has the lowest transactional fees in the world.It has fewer risks and irreversible transaction benefitting merchants.It is fully Secured and control by the cryptographic encryption algorithm.It is the transparent & neutral mode of administration as anyone can check data in real-time.21) What are the disadvantages of Bitcoin?Following are the disadvantages: of bitcoins.Degree of Acceptance: In Bitcoin, the Degree of Acceptance is very low because many people are still unaware of its benefits.Volatile: Total number of Bitcoins in circulation is very small, so even a small change can make the price of the Bitcoin volatile.Ongoing Development: Bitcoins software is still in beta form, and many incomplete features are in active development22) What is mean by Unconfirmed Transaction?An unconfirmed transaction is that transaction that has not been included in a block, and not completed also. Every transaction requires at least one confirmation to complete the transaction.The common reasons for unconfirmed transactions are:You have made the transfer. The Bitcoin network needs at least 10 minutes to include the transaction in a block.The blockchain fee is very low. Thus, the lower the transaction fee, the lower your transaction's priority in the Bitcoin network. Therefore, it takes longer confirmation to be a valid transaction.23) Who controls the Bitcoin network?Bitcoin network is the term used to describe all the servers which are mining the various transactions undertaken with bitcoin. No one particularly can control the Bitcoin network. All Bitcoin users around the world control it. To be compatible with each other, all bitcoin users need to use software that is complying with the same rules. Bitcoin mining can only work correctly with a complete consensus among all users. Therefore, all users and developers have a strong incentive to protect this consensus.24) What is the price of one Bitcoin? Can I buy a part of one Bitcoin?The buying rate for one Bitcoin as of April 2019 is approximately 3,67,569.51 Indian Rupees. The price of bitcoin would be changed every second. If you do not want to buy one bitcoin whole, you can buy a fraction of a Bitcoin also. It is because each bitcoin can be divided up to 8 decimals(0.00000001). For instance, you can buy Bitcoin for Rs 1000 or Rs 5,000.25) Is it legal to buy and sell Bitcoin from India?It is not illegal to buy and sell bitcoins in India. There is no law in India which declares it illegal. In India, the cusp of a digital revolution is yet to recognize the cryptocurrency officially. The Reserve bank of India(RBI), which regulates Indian rupee, had earlier cautioned users, holders and traders of Virtual currencies including Bitcoins.Any central bank or monetary authority do not authorize the creation, trading or usage of Bitcoins as a medium for payment. There are no regulatory approvals, registration or authorization is stated to have been obtained by the entities concerned for carrying on such activities. However, the central bank has not unequivocally banned Bitcoins in the country.26) How do bitcoin transactions work?A transaction is a transfer of value between Bitcoin wallets of sender and receiver in the blockchain network. Each bitcoin transaction is composed of an amount. The amount is the input (sending address), an output (receiver's address), and the private keys that allow spending of Bitcoins from an individual's account. The blockchain is a database which maintains the transaction history since bitcoin's inception.27) What steps should you take to safeguard themselves from Bitcoin fraud?The basic advice is that you should not invest in anything that you does not understand. There are many schemes and scams available around bitcoin mining. A blockchain is a high-risk technology, it has potential, but we never guarantee anything. There is no way as a guaranteed return in the Bitcoin world. On the Zebpay home page, there is a section that lists about frauds and schemes and advises users on how to protect themselves.28) What is the difference between Bitcoin and Blockchain?SNBlockchainBitcoin1.Blockchain is a ledger with cryptographic integrity.Bitcoin is a cryptocurrency.2.Blockchain can easily transfer anything from currencies to property rights of stocks.Bitcoin is limited to trading as currency.3.It has a broad scope because of open-source.It has a limited scope and is less flexible.4.It provides a low cost safe and secure environment for a peer-to-peer transaction.To simplify and increase the speed of transaction without much of government restrictions.5.It is transparent as it must comply with KYC for every business.It can be termed as anonymous because there are no regulatory framework and standards that have been followed by bitcoin.
More detailsPublished - Tue, 06 Dec 2022
Created by - Admin s
A list of top frequently asked AWS Interview Questions and answers are given below.1) What is AWS?AWS stands for Amazon Web Services. It is a service which is provided by the Amazon that uses distributed IT infrastructure to provide different IT resources on demand. It provides different services such as an infrastructure as a service, platform as a service, and software as a service.2) What are the components of AWS?The following are the main components of AWS are:Simple Storage Service: S3 is a service of aws that stores the files. It is object-based storage, i.e., you can store the images, word files, pdf files, etc. The size of the file that can be stored in S3 is from 0 Bytes to 5 TB. It is an unlimited storage medium, i.e., you can store the data as much you want. S3 contains a bucket which stores the files. A bucket is like a folder that stores the files. It is a universal namespace, i.e., name must be unique globally. Each bucket must have a unique name to generate the unique DNS address.Elastic Compute Cloud: Elastic Compute Cloud is a web service that provides resizable compute capacity in the cloud. You can scale the compute capacity up and down as per the computing requirement changes. It changes the economics of computing by allowing you to pay only for the resources that you actually use.Elastic Block Store: It provides a persistent block storage volume for use with EC2 instances in aws cloud. EBS volume is automatically replicated within its availability zone to prevent the component failure. It offers high durability, availability, and low-latency performance required to run your workloads.CloudWatch: It is a service which is used to monitor all the AWS resources and applications that you run in real time. It collects and tracks the metrics that measure your resources and applications. If you want to know about the CloudWatch in detail, then click on the below link: Click hereIdentity Access Management: It is a service of aws used to manage users and their level of access to the aws management console. It is used to set users, permissions, and roles. It allows you to grant permission to the different parts of the aws platform. If you want to know about the IAM, then click the below link: Click hereSimple Email Service: Amazon Simple Email Service is a cloud-based email sending service that helps digital marketers and application developers to send marketing, notification, and transactional emails. This service is very reliable and cost-effective for the businesses of all the sizes that want to keep in touch with the customers.Route53: It is a highly available and scalable DNS (Domain Name Service) service. It provides a reliable and cost-effective way for the developers and businesses to route end users to internet applications by translating domain names into numeric IP addresses. If you want to know more about Route53 in detail, then click on the link given below: Click here3) What are Key-pairs?An Amazon EC2 uses public key cryptography which is used to encrypt and decrypt the login information. In public key cryptography, the public key is used to encrypt the information while at the receiver's side, a private key is used to decrypt the information. The combination of a public key and the private key is known as key-pairs. Key-pairs allows you to access the instances securely.Play Videox4) What is S3?S3 is a storage service in aws that allows you to store the vast amount of data. To know more about S3, click on the link given below:Click here5) What are the pricing models for EC2 instances?There are four pricing models for EC2 instances:On-Demand instanceOn-Demand pricing is also known as pay-as-you-go. Pay-as-you-go is a pricing model that allows you to pay only for those resources that you use.You need to pay for the compute capacity by per hour or per second that depends on which instances you run.On-Demand instance does not require any upfront payments.While using On-Demand instance, you can increase or decrease the compute capacity based on the requirements of your application.On-Demand instances are recommended for those applications which are of short term and unpredictable workloads.Users that want low cost and flexibility on EC2 instances with no upfront payments.On-Demand instances are used for those applications which have been developed or tested on EC2 for the first time.Reserved instanceReserved instance is the second most important pricing model that reduces the overall cost of your AWS environment by making an upfront payment for those services that you know will be used in the future.Reserved instances provide a discount of up to 75% as compared to On-Demand instance.Reserved instances are assigned to a specific Availability zone that reserves the compute capacity for you so that you can use whenever you need.Reserved instances are mainly recommended for those applications that have steady state and require reserve capacity.Customers who want to use the EC2 over 1 to 3 term can use the reserved instance to reduce the overall computing costs.Spot instanceSpot instances consist of unused capacity which is available at a highly discounted rate.It offers up to 90% discount as compared to On-Demand instance.Spot instances are mainly recommended for those applications which have flexible start and end times.It is useful when applications require computing capacity at a very low price.It is useful when applications require additional amount of computing capacity at an urgent need.Dedicated HostsIt is a physical EC2 server which is dedicated for your use. It reduces the overall costs by providing you a VPC that comprise of a dedicated hardware.6) What is AWS Lambda?AWS Lambda is a compute service that runs your code without managing servers. Lambda function runs your code whenever needed. You need to pay only when your code is running. If you want to know more about the AWS Lambda, then click on the link shown below:Click Here7) How many buckets can be created in S3?By default, you can create up to 100 buckets.8) What is Cross Region Replication?Cross Region Replication is a service available in aws that enables to replicate the data from one bucket to another bucket which could be in a same or different region. It provides asynchronous copying of objects, i.e., objects are not copied immediately. If you want to know more about the Cross Region Replication, then click on the link shown below:Click Here9) What is CloudFront?CloudFront is a computer delivery network which consists of distributed servers that delivers web pages and web content to a user based on the geographic locations of a user. If you want to know more about the CloudFront, then click on the link shown below:Click Here10) What are Regions and Availability Zones in aws?Regions: A region is a geographical area which consists of 2 or more availability zones. A region is a collection of data centers which are completely isolated from other regions.Availability zones: An Availability zone is a data center that can be somewhere in the country or city. Data center can have multiple servers, switches, firewalls, load balancing. The things through which you can interact with the cloud reside inside the Data center.If you want to know more about the Availability zone and region, then click on the link shown below:Click Here11) What are edge locations in aws?Edge locations are the endpoints in aws used for caching content. If you want to know more about the edge locations, then click on the link shown below:Click Here12) What is the minimum and maximum size that you can store in S3?The minimum size of an object that you can store in S3 is 0 bytes and the maximum size of an object that you can store in S3 is 5 TB.13) What are EBS Volumes?Elastic Block Store is a service that provides a persistent block storage volume for use with EC2 instances in aws cloud. EBS volume is automatically replicated within its availability zone to prevent from the component failure. It offers high durability, availability, and low-latency performance required to run your workloads. . If you want to know more about the EBS Volumes, then click on the link shown below:Click Here14) What is Auto Scaling?Auto Scaling is a feature in aws that automatically scales the capacity to maintain steady and predictable performance. While using auto scaling, you can scale multiple resources across multiple services in minutes. If you are already using Amazon EC2 Auto- scaling, then you can combine Amazon EC2 Auto-Scaling with the Auto-Scaling to scale additional resources for other AWS services.Benefits of Auto ScalingSetup Scaling QuicklyIt sets the target utilization levels of multiple resources in a single interface. You can see the average utilization level of multiple resources in the same console, i.e., you do not have to move to the different console.Make Smart Scaling DecisionsIt makes the scaling plans that automate how different resources respond to the changes. It optimizes the availability and cost. It automatically creates the scaling policies and sets the targets based on your preference. It also monitors your application and automatically adds or removes the capacity based on the requirements.Automatically maintain performanceAuto Scaling automatically optimize the application performance and availability even when the workloads are unpredictable. It continuously monitors your application to maintain the desired performance level. When demand rises, then Auto Scaling automatically scales the resources.15) What is AMI?AMI stands for Amazon Machine Image. It is a virtual image used to create a virtual machine within an EC2 instance. If you want to know more about the AMI, then click on the link shown below:Click Here16) Can a AMI be shared?Yes, an AMI can be shared.17) What is an EIP?EIP (Elastic IP address) is a service provided by an EC2 instance. It is basically a static IP address attached to an EC2 instance. This address is associated with your AWS account not with an EC2 instance. You can also disassociate your EIP address from your EC2 instance and map it to another EC2 instance in your AWS account.Let's understand the concept of EIP through an example:Suppose we consider the website www.javatpoint.com points to the instance which has a public IP address. When instance is restarted, then AWS takes another public IP address from the pool and the previous public IP address is no longer valid. Due to this reason, the original link is no longer available between the website and EC2 instance. To overcome from such situation, Elastic IP address or static address is used which does not change.18) What are the different storage classes in S3?Storage classes are used to assist the concurrent loss of data in one or two facilities. Each object in S3 is associated with some storage class. Amazon S3 contains some storage classes in which you can store your objects. You can choose a storage class based on your requirements and these storage classes offer high durability. To know more about the storage classes and its types, click on the link given below:Click Here19) How can you secure the access to your S3 bucket?S3 bucket can be secured in two ways:ACL (Access Control List)ACL is used to manage the access of resources to buckets and objects. An object of each bucket is associated with ACL. It defines which AWS accounts have granted access and the type of access. When a user sends the request for a resource, then its corresponding ACL will be checked to verify whether the user has granted access to the resource or not.When you create a bucket, then Amazon S3 creates a default ACL which provides a full control over the AWS resources.Bucket PoliciesBucket policies are only applied to S3 bucket. Bucket policies define what actions are allowed or denied. Bucket policies are attached to the bucket not to an S3 object but the permissions define in the bucket policy are applied to all the objects in S3 bucket.The following are the main elements of Bucket policy:SidA Sid determines what the policy will do. For example, if an action that needs to be performed is adding a new user to an Access Control List (ACL), then the Sid would be AddCannedAcl. If the policy is defined to evaluate IP addresses, then the Sid would be IPAllow.Effect: An effect defines an action after applying the policy. The action could be either to allow an action or to deny an action.PrincipalA Principal is a string that determines to whom the policy is applied. If we set the principal string as '*', then the policy is applied to everyone, but it is also possible that you can specify individual AWS account.ActionAn Action is what happens when the policy is applied. For example, s3:Getobject is an action that allows to read object data.ResourceThe Resource is a S3 bucket to which the statement is applied. You cannot enter a simply bucket name, you need to specify the bucket name in a specific format. For example, the bucket name is javatpoint-bucket, then the resource would be written as "arn:aws:s3""javatpoint-bucket/*".20) What are policies and what are the different types of policies?Policy is an object which is associated with a resource that defines the permissions. AWS evaluate these policies when user makes a request. Permissions in the policy determine whether to allow or to deny an action. Policies are stored in the form of a JSON documents.AWS supports six types of policies:Identity-based policiesResource-based policiesPermissions boundariesOrganizations SCPsAccess Control ListsSession policiesIdentity-based policiesIdentity-based policies are the permissions stored in the form of JSON format. This policy can be attached to an identity user, group of users or role. It determines the actions that the users can perform, on which resources, and under what conditions.Identity-based policies are further classified into two categories:Managed Policies: Managed Policies are the identity-based policies which can be attached to multiple users, groups or roles. There are two types of managed policies:AWS Managed PoliciesAWS Managed Policies are the policies created and managed by AWS. If you are using the policies first time, then we recommend you to use AWS Managed Policies.Custom Managed PoliciesCustom Managed Policies are the identity-based policies created by user. It provides more precise control over the policies than AWS Managed Policies.Inline PoliciesInline Policies are the policies created and managed by user. These policies are encapsulated directly into a single user, group or a role.Resource-Based PoliciesResource-based policies are the policies which are attached to the resource such as S3 bucket. Resource-based policies define the actions that can be performed on the resource and under what condition, these policies can be applied.Permissions boundariesPermissions boundaries are the maximum permissions that identity-based policy can grant to the entity.Service Control Policies (SCPs)Service Control Policies are the policies defined in a JSON format that specify the maximum permissions for an organization. If you enable all the features in an Organization, then you can apply Service Control Policies to any or all of your AWS accounts. SCP can limit the permission on entities in member accounts as well as AWS root user account.Access Control Lists (ACLs)ACL defines the control that which principals in another AWS account can access the resource. ACLs cannot be used to control the access of a principal in a different AWS account. It is the only policy type which does not have the JSON policy document format.21) What are different types of instances?Following are the different types of instances:General Purpose Instance typeGeneral purpose instances are the instances mainly used by the companies. There are two types of General Purpose instances: Fixed performance (eg. M3 and M4) and Burstable performance (eg. T2). Some of the sectors use this instance such as Development environments, build servers, code repositories, low traffic websites and web applications, micro-services, etc.Following are the General Purpose Instances:T2 instances: T2 instances are the instances that receive CPU credits when they are sitting idle and they use the CPU credits when they are active. These instances do not use the CPU very consistently, but it has the ability to burst to a higher level when required by the workload.M4 instances: M4 instances are the latest version of General purpose instances. These instances are the best choice for managing memory and network resources. They are mainly used for the applications where demand for the micro-servers is high.M3 instances: M3 instance is a prior version of M4. M4 instance is mainly used for data processing tasks which require additional memory, caching fleets, running backend servers for SAP and other enterprise applications.Compute Optimized Instance typeCompute Optimized Instance type consists of two instance types: C4 and C3.C3 instance: C3 instances are mainly used for those applications which require very high CPU usage. These instances are mainly recommended for those applications that require high computing power as these instances offer high performing processors.C4 instance: C4 instance is the next version of C3 instance. C4 instance is mainly used for those applications that require high computing power. It consists of Intel E5-2666 v3 processor and use Hardware virtualization. According to the AWS specifications, C4 instances can run at a speed of 2.9 GHz, and can reach to a clock speed of 3.5 GHz.GPU InstancesGPU instances consist of G2 instances which are mainly used for gaming applications that require heavy graphics and 3D application data streaming. It consists of a high-performance NVIDIA GPU which is suitable for audio, video, 3D imaging, and graphics streaming kinds of applications. To run the GPU instances, NVIDIA drivers must be installed.Memory Optimized InstancesMemory Optimized Instances consists of R3 instances which are designed for memory- intensive applications. R3 instance consists of latest Intel Xeon lvy Bridge processor. R3 instance can sustain a memory bandwidth of 63000 MB/sec. R3 instance offers a high- performance databases, In memory analytics, and distributed memory caches.Storage Optimized InstancesStorage Optimized Instances consist of two types of instances: I2 and D2 instances.I2 instance: It provides heavy SSD which is required for the sequential read, and write access to a large data sets. It also provides random I/O operations to your applications. It is best suited for the applications such as high-frequency online transaction processing systems, relational databases, NoSQL databases, Cache for in-memory databases, Data warehousing applications and Low latency Ad- Tech serving applications.D2 instance: D2 instance is a dense storage instance which consists of a high-frequency Intel Xeon E5-2676v3 processors, HDD storage, High disk throughput.22) What is the default storage class in S3?The default storage class is Standard Frequently Accessed.23) What is a snowball?Snowball is a petabyte-scale data transport solution that uses secure appliances to transfer large amounts of data into and out of aws cloud. If you want to know more about the Snowball, click on the link given below:Click Here24) Difference between Stopping and Terminating the instances?Stopping: You can stop an EC2 instance and stopping an instance means shutting down the instance. Its corresponding EBS volume is still attached to an EC2 instance, so you can restart the instance as well.Terminating: You can also terminate the EC2 instance and terminating an instance means you are removing the instance from your AWS account. When you terminate an instance, then its corresponding EBS is also removed. Due to this reason, you cannot restart the EC2 instance.25) How many Elastic IPs can you create?5 elastic IP addresses that you can create per AWS account per region.26) What is a Load Balancer?Load Balancer is a virtual machine that balances your web application load that could be Http or Https traffic that you are getting in. It balances a load of multiple servers so that no web server gets overwhelmed. To know more, click on the link given below:Click Here27) What is VPC?VPC stands for Virtual Private Cloud. It is an isolated area of the AWS cloud where you can launch AWS resources in a virtual network that you define. It provides a complete control on your virtual networking environment such as selection of an IP address, creation of subnets, configuration of route tables and network gateways. To know more about VPC, click on the link given below:Click Here28) What is VPC peering connection?A VPC peering connection is a networking connection that allows you to connect one VPC with another VPC through a direct network route using private IP addresses.By using VPC peering connection, instances in different VPC can communicate with each other as if they were in the same network.You can peer VPCs in the same account as well as with the different AWS accountTo know more about, click on the link given below: Click Here29) What are NAT Gateways?NAT stands for Network Address Translation. It is an aws service that enables to connect an EC2 instance in private subnet to the internet or other AWS services. If you want to know more about NAT Gateways, click on the link shown below:Click Here30) How can you control the security to your VPC?You can control the security to your VPC in two ways:Security GroupsIt acts as a virtual firewall for associated EC2 instances that control both inbound and outbound traffic at the instance level. To know more about Security Groups, click on the link given below: Click HereNetwork access control lists (NACL)It acts as a firewall for associated subnets that control both inbound and outbound traffic at the subnet level. To know more about NACL, click on the link given below: Click Here31) What are the different database types in RDS?Following are the different database types in RDS:Amazon AuroraIt is a database engine developed in RDS. Aurora database can run only on AWS infrastructure not like MySQL database which can be installed on any local device. It is a MySQL compatible relational database engine that combines the speed and availability of traditional databases with the open source databases. To know more about Amazon Aurora, click on the link given below: Click HerePostgre SQLPostgreSQL is an open source relational database for many developers and startups.It is easy to set up, operate, and can also scale PostgreSQL deployments in the cloud.You can also scale PostgreSQL deployments in minutes with cost-efficient.PostgreSQL database manages time-consuming administrative tasks such as PostgreSQL software installation, storage management, and backups for disaster recovery.MySQLIt is an open source relational database.It is easy to set up, operate, and can also scale MySQL deployments in the cloud.By using Amazon RDS, you can deploy scalable MySQL servers in minutes with cost-efficient.MariaDBIt is an open source relational database created by the developers of MySQL.It is easy to set up, operate, and can also scale MariaDB server deployments in the cloud.By using Amazon RDS, you can deploy scalable MariaDB servers in minutes with cost-efficient.It frees you from managing administrative tasks such as backups, software patching, monitoring, scaling and replication.OracleIt is a relational database developed by Oracle.It is easy to set up, operate, and can also scale Oracle database deployments in the cloud.You can deploy multiple editions of Oracle in minutes with cost-efficient.It frees you from managing administrative tasks such as backups, software patching, monitoring, scaling and replication.You can run Oracle under two different licensing models: "License Included" and "Bring Your Own License (BYOL)". In License Included service model, you do need have to purchase the Oracle license separately as it is already licensed by AWS. In this model, pricing starts at $0.04 per hour. If you already have purchased the Oracle license, then you can use the BYOL model to run Oracle databases in Amazon RDS with pricing starts at $0.025 per hour.SQL ServerSQL Server is a relational database developed by Microsoft.It is easy to set up, operate, and can also scale SQL Server deployments in the cloud.You can deploy multiple editions of SQL Server in minutes with cost-efficient.It frees you from managing administrative tasks such as backups, software patching, monitoring, scaling and replication.32) What is Redshift?Redshift is a fast, powerful, scalable and fully managed data warehouse service in the cloud.It provides ten times faster performance than other data warehouse by using machine learning, massively parallel query execution, and columnar storage on high-performance disk.You can run petabytes of data in Redshift datawarehouse and exabytes of data in your data lake built on Amazon S3.To know more about Amazon Redshift, click on the link given below: Click Here33) What is SNS?SNS stands for Simple Notification Service. It is a web service that provides highly scalable, cost-effective, and flexible capability to publish messages from an application and sends them to other applications. It is a way of sending messages. If you want to know more about SNS, click on the link given below:Click Here34) What are the different types of routing policies in route53?Following are the different types of routing policies in route53:Simple Routing PolicySimple Routing Policy is a simple round-robin policy which is applied to a single resource doing the function for the domain, For example, web server is sending the content to a website where web server is a single resource.It responds to DNS queries based on the values present in the resource.Weighted Routing PolicyWeighted Routing Policy allows you to route the traffic to different resources in specified proportions. For example, 75% in one server, and 25% in another server.Weights can be assigned in the range from 0 to 255.Weight Routing policy is applied when there are multiple resources accessing the same function. For example, web servers accessing the same website. Each web server will be given a unique weight number.Weighted Routing Policy associates the multiple resources to a single DNS name.Latency-based Routing PolicyLatent-based Routing Policy allows Route53 to respond to the DNS query at which data center gives the lowest latency.Latency-based Routing policy is used when there are multiple resources accessing the same domain. Route53 will identify the resource that provides the fastest response with lowest latency.Failover Routing PolicyGeolocation Routing Policy35) What is the maximum size of messages in SQS?The maximum size of message in SQS IS 256 KB.36) Differences between Security group and Network access control list?Security GroupNACL (Network Access Control List)It supports only allow rules, and by default, all the rules are denied. You cannot deny the rule for establishing a connection.It supports both allow and deny rules, and by default, all the rules are denied. You need to add the rule which you can either allow or deny it.It is a stateful means that any changes made in the inbound rule will be automatically reflected in the outbound rule. For example, If you are allowing an incoming port 80, then you also have to add the outbound rule explicitly.It is a stateless means that any changes made in the inbound rule will not reflect the outbound rule, i.e., you need to add the outbound rule separately. For example, if you add an inbound rule port number 80, then you also have to explicitly add the outbound rule.It is associated with an EC2 instance.It is associated with a subnet.All the rules are evaluated before deciding whether to allow the traffic.Rules are evaluated in order, starting from the lowest number.Security Group is applied to an instance only when you specify a security group while launching an instance.NACL has applied automatically to all the instances which are associated with an instance.It is the first layer of defense.It is the second layer of defense.37) What are the two types of access that you can provide when you are creating users?There are two types of access:Console AccessIf the user wants to use the Console Access, a user needs to create a password to login in an AWS account.Programmatic accessIf you use the Programmatic access, an IAM user need to make an API calls. An API call can be made by using the AWS CLI. To use the AWS CLI, you need to create an access key ID and secret access key.38) What is subnet?When large section of IP address is divided into smaller units is known as subnet.A Virtual Private Cloud (VPC) is a virtual network provided to your AWS account. When you create a virtual cloud, you need to specify the IPv4 addresses which is in the form of CIDR block. After creating a VPC, you need to create the subnets in each availability zone. Each subnet has a unique ID. When launching instances in each availability zone, it will protect your applications from the failure of a single location.39) Differences between Amazon S3 and EC2?S3It is a storage service where it can store any amount of data.It consists of a REST interface and uses secure HMAC-SHA1 authentication keys.EC2It is a web service used for hosting an application.It is a virtual machine which can run either Linux or Windows and can also run the applications such as PHP, Python, Apache or other databases.40) Can you establish a peering connection to a VPC in a different region?No, it's not possible to establish a peering connection to a VPC in a different region. It's only possible to establish a peering connection to a VPC in the same region.41) How many subnets can you have per VPC?You can have 200 subnets per VPC.42) When EC2 officially launched?EC2 was officially launched in 2006.43) What is Amazon Elasticache?An Amazon Elasticache is a web service allows you to easily deploy, operate, and scale an in-memory cache in the cloud. To know more about the Amazon Elasticache, click on the link given below:Click Here44) What are the types of AMI provided by AWS?There are two types of AMI provided by AWS:Instance store backedAn instance-store backed is an EC2 instance whose root device resides on the virtual machine's hard drive.When you create an instance, then AMI is copied to the instance.Since "instance store-backed" instances root device is stored in the virtual machine's hard drive, so you cannot stop the instance. You can only terminate the instance, and if you do so, the instance will be deleted and cannot be recovered.If the virtual machine's hard drive fails, then you can lose your data.You need to leave this instance-store instance in a running state until you are completely done with it.You will be charged from the moment when your instance is started until your instance is terminated.EBS backedAn "EBS backed" instance is an EC2 instance that uses EBS volume as a root deviceEBS volumes are not tied to a virtual hardware, but they are restricted to an availability zone. This means that EBS volume is moved from one machine to another machine within the same availability zone.If the virtual machine's fails, then the virtual machine can be moved to another virtual machine.The main advantage of "EBS backed" over "instance store-backed" instances is that it can be stopped. When an instance is in a stopped state, then EBS volume can be stored for a later use. The virtual machine is used for some other instance. In stopped state, you are not charged for the EBS storage.45) What is Amazon EMR?An Amazon EMR stands for Amazon Elastic MapReduce. It is a web service used to process the large amounts of data in a cost-effective manner. The central component of an Amazon EMR is a cluster. Each cluster is a collection of EC2 instances and an instance in a cluster is known as node. Each node has a specified role attached to it known as a node type, and an Amazon EMR installs the software components on node type.Following are the node types:Master nodeA master node runs the software components to distribute the tasks among other nodes in a cluster. It tracks the status of all the tasks and monitors the health of a cluster.Core nodeA core node runs the software components to process the tasks and stores the data in Hadoop Distributed File System (HDFS). Multi-node clusters will have at least one core node.Task nodeA task node with software components processes the task but does not store the data in HDFS. Task nodes are optional.46) How to connect EBS volume to multiple instances?You cannot connect the EBS volume to multiple instances. But, you can connect multiple EBS volumes to a single instance.47) What is the use of lifecycle hooks in Autoscaling?Lifecycle hooks perform custom actions by pausing instances when Autoscaling group launches or terminates an instance. When instance is paused, an instance moves in a wait state. By default, an instance remains in a wait state for 1 hour. For example, when you launch a new instance, lifecycle hooks pauses an instance. When you pause an instance, you can install a software on it or make sure that an instance is completely ready to receive the traffic.48) What is Amazon Kinesis Firehose?An Amazon Kinesis Firehose is a web service used to deliver real-time streaming data to destinations such as Amazon Simple Storage Service, Amazon Redshift, etc. To know more about Amazon Kinesis Firehose, click on the link given below:Click Here49) What is the use of Amazon Transfer Acceleration Service?An Amazon Transfer Acceleration Service is a service that enables fast and secure transfer of data between your client and S3 bucket. To know more about Amazon Transfer Acceleration Service, click on the link given below:Click Here50) How will you access the data on EBS in AWS?EBS stands for Elastic Block Store. It is a virtual disk in a cloud that creates the storage volume and attach it to the EC2 instances. It can run the databases as well as can store the files. All the files that it store can be mounted as a file system which can be accessed directly. To know more about EBS, click on the link given below:Click Here51) Differences between horizontal scaling and vertical scaling?Vertical scaling means scaling the compute power such as CPU, RAM to your existing machine while horizontal scaling means adding more machines to your server or database. Horizontal scaling means increasing the number of nodes, and distributing the tasks among different nodes.
More detailsPublished - Tue, 06 Dec 2022
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A list of top frequently asked QA Interview Questions or Quality Assurance Interview Questions and answers are given below.1) What is Quality Assurance?QA stands Quality Assurance. QA is a set of activities designed to ensure that the developed software meets all the specifications or requirements mentioned in the SRS document.QA follows the PDCA cycles:PlanThe plan is a phase in Quality Assurance in which the organization determines the processes which are required to build a high-quality software product.Play VideoxDoDo is a phase of development and testing the processes.CheckThis phase is used for monitoring the processes and verifies whether these processes meet the user requirements or not.ActThe Act is a phase for implementing the actions required to improve the processes.2) What is the difference between Quality Assurance and Software testing?The following is the list of differences between Quality Assurance and Software testing:Quality AssuranceSoftware testingActivitiesQuality Assurance is a set of activities used to ensure that the developed software meets all the user requirements.Software testing is an activity performed after the development phase to check whether the actual results match the expected results to ensure that the software is bug-free. In short, we can say that software testing is verification of application under test.ActivitiesIt involves activities that include the implementation of processes, procedures, and standards.It involves activities that include verification of testing.OrientationIt is a process-oriented, i.e., it checks the processes to ensure that quality software is delivered to the client.It is a product-oriented, i.e., checking the functionality of a software.Activity typePreventiveCorrectiveObjectiveThe main objective of Quality Assurance is to deliver quality software.The main objective of software testing is to find the bugs in the developed software.3) How the build and release differ from one another, write down the difference between build and release?Build is defined as when the software is given to the testing team by the development team.Release It is defined as when the software is handed over to the users by the tester and developer.4) Define bug leakage and bug release?Bug leakage is defined as the bug not found by the testing team but found by the end users. Bug release it is defined when the software is released by the tester in the market knowing that bug is present in the release. These types of bugs have low priority and severity. This type of situation arises when customers want the software on time than the delay in getting the software and the cost involved in correcting the bugs.5) What are the solutions for the software development problem?There are five different solutions for the software development problem.The requirements for software development should be clear, complete, and agreed by all, setting up the requirements criteria.Next thing is the realistic schedule like time for planning, designing, testing, fixing bugs, and re-testing.It requires sufficient testing, starts the testing immediately after one or more module development.Use of group communication tools.Use rapid prototype during the design phase so that it can be easy for the customer to find what to expect.6) Explain the types of documents in Software Quality Assurance?The following are the types of documents in Software Quality Assurance:Requirement DocumentAll the functionalities are to be added in the application are documented in terms of Requirements, and the document is known as Requirement document. This Requirement document is made by the collaboration of various people in the project team like developers, testers, Business Analysts, etc.Test MetricsTest Metrics is a quantitative measure that determines the quality and effectiveness of the testing process.Test planIt defines the strategy which will be applied to test an application, the resources that will be used, the test environment in which testing will be performed, and scheduling of test activities will be done.Test casesA test case is a set of steps, and conditions used at the time of testing. This activity is performed to verify whether all the functionalities of software are working properly or not. There can be various types of test cases such as logical, functional, error, negative test cases, physical test cases, UI test cases, etc.Traceability matrixTraceability matrix is a table that traces and maps the user requirements with test cases. The main aim of Requirement Traceability Matrix is to see that all test cases are covered so that no functionality miss during the software testing.Test scenarioA test scenario is a collection set of test cases which helps the testing team to determine the positive and negative aspects of a project.7) What is the rule of a "Test Driven Development"?In Test Driven Development, test cases are prepared before writing the actual code. It means you have to write the test case before the real development of the application.Test Driven Development cycle:Write the test casesExecute the test casesIf the test case fails, then changes are made to make it correctRepeat the process8) What is traceability matrix?Traceability matrix is a document that maps and traces user requirements with test cases. The main aim of Requirement Traceability Matrix is to see that all test cases are covered so that no functionality miss during the software testing.9) Write down the differences between the responsibilities of QA and programmers?Differences in responsibilities are as:Sr. No.QA ResponsibilityProgrammer Responsibility1.QA team is concerned for process QualityProgrammers are concerned for product quality2.QA ensures that the processes used for developing the product of high qualityProgrammers used these processes so that the end product is of good qualityAny issue found during the execution of the process by the programmers is communicated to the QA so that they can improve the process.10) What is the difference between Verification and Validation?VerificationValidationVerification is the process of evaluating the steps during the development phase to determine whether they meet the user requirements or not.Validation is the process of evaluating the product after the development process to determine whether it meets the specified requirement.Verification is static testing.Validation is dynamic testing.Verification testing is performed before validation.Validation is performed after verification.It does not involve in executing the code.It involves in executing the code.It involves activities such as reviews, walkthroughs, inspections, and desk checking, etc.It involves methods such as black box testing, white box testing and non-functional testing.It finds the bugs before the development cycle.It finds the bugs after the development cycle.It conforms to the requirements specified in the SRS document.It checks whether it meets the specified requirements or not.QA team performs verification in which they verify that the software is according to the requirements specified in the SRS document.Software tester performs testing of a product.11) Define the key challenges faced during software testing?The application should be stable for testing.Testing should be under a time constraint.Which tests should execute first?Testing the complete application.Regression TestingLack of skilled testers.Changing requirements.Lack of resources, training, and tools.12) What is the difference between Retesting and Regression testing?RegressionRetestingRegression is a type of testing used to verify whether the new changes in the code have affected the unchanged features or not.Retesting is the testing of modules that have been failed in the last execution.The main aim of Regression testing is that any changes made in the code should not affect the existing functionalities.Retesting is the testing which is performed on the defects that have been fixed.It is generic testing as it can be performed at any time whenever the changes made in the code.It is planned testing.It is performed on the test cases that have been passed.It is performed on the test cases that have been failed.Automation can be done for regression testing, while manual testing will be expensive and time consuming.To perform the Retesting, we cannot automate the test cases.Defect verification does not come under the Regression testing.Defect verification comes under the Retesting.Based on the availability of resources, regression testing is performed in parallel with the retesting.The priority of retesting is more than the regression testing, so it always performed before the regression testing.13) Define the role of QA in Software Development?QA stands for Quality Assurance. QA team persuades the quality by monitoring the whole development process. QA tracks the outcome and adjusting processes to meet the expectation.Role of Quality Assurance are:QA team is responsible for monitoring the process to be carried out for development.Responsibilities of the QA team are planning, testing, execution process.QA Lead creates the time table and agrees on a Quality Assurance plan for the product.QA team communicated the QA process to the team members.QA team ensures traceability of test cases to requirements.14) Describe the dimensions of the risk in QA?The dimensions of the risk are:Schedule: Unrealistic Schedules, to develop a huge software in a single day.Client: Ambiguous requirements definition, requirements are not clear, changes in requirement.Human Resource: Non - availability of sufficient resources with the skill level expected in the project.System Resources: Non-availability of acquiring all critical resources, either hardware and software tools or license for software will have an adverse effect.Quality: Compound factors like lack of resources along with a tight delivery schedule and frequent changes to the requirement will affect the quality of the product tested.15) What is the test ware?Test ware is a term used to describe all the materials used to perform the test. Test ware includes test plans, test cases, test data, and any other items needed to perform and design a test.16) What is Monkey testing?Monkey testing is a type of black box testing used to test the application by providing random inputs to check the system behavior such as to check the system, whether it is crashing or not.This type of testing is performed automatically whenever the user provides the random inputs to check the system behaviorThere is no need to create test cases to perform monkey testing.It can also be automated, i.e., we can write the programs or scripts to generate random inputs to check the system behavior.This technique is useful when we are performing stress or load testing.There are two types of monkeys:Smart monkeysDumb monkeysSmart MonkeysSmart monkeys are those which have a brief idea about the application.They know that where the pages of an application will redirect to which page.They also know that the inputs that they are providing are valid or invalid.If they find any error, then they are smart enough to file a bug.They also know that what are the menus and buttons.Dumb MonkeysDumb Monkeys are those which have no idea about the application.They do not know about the pages of an application will redirect to.They provide random inputs, and they do not know about the starting and ending point of the application.They do not know much about the application, but still, they find bugs such as environmental failure or hardware failure.They also do not know much about the functionality and UI of an application.17) Write the differences between Preventive and Reactive approaches?Preventive Approach: It is also known as the Verification process. Preventive is the approach to prevent defects. In this approach, tests are designed in its early stages of Software Development Lifecycle before the software has developed. In this approach, testers try to prevent defects in the early stages; it comes under Quality Analysis.Reactive Approach: It is also known as Validation Process. This approach is to identify defects. In this approach, tests are designed to execute after the software's development. In this approach, we try to find out the defects. It comes under Quality Control.18) What is the Quality Audit?An Audit is defined as on-site verification activity, such as inspection or examination, of a processor quality system. Quality Audit is the process of systematic analysis of a quality system carried out by an internal or external quality auditor, or an audit team. Quality Audits are performed at predefined time intervals and ensure that the institution has clearly defined internal system monitoring procedures linked to effective action. Audits are an essential management tool to be used for verifying objective evidence of processes.19) What is a test plan?The Test Plan document is a document which contains the plan for all the testing activities to deliver a quality product. The test Plan document is derived from many activities such as product description, SRS, or Use Case documents for all future events of the project. The Test Lead usually prepares it, or Test manager and the focus of the document is to describe what to test, how to test when to test, who will do what test.20) How do you decide when you have tested enough?This is one of the most crucial questions. As a project manager or project lead, sometimes we might face a situation to call off the testing to release the product early. In those cases, we have to decide whether the testers have tested the product enough or not.There are many factors involved in real-time projects to decide when to stop testing:If we reach Testing deadlines or release deadlinesBy entering the decided pass percentage of test cases.In the real-time project, if the risk in the project is under the acceptable limit.If all the high priority bugs and blockers have been fixed.If we meet the acceptance criteria.21) How to design test cases?There are mainly two techniques to design the test cases:Black box testingIt is a specification-based technique where the testers view the software as a black box with inputs and outputs.In black box testing, the testers do not know about how the software is structured inside the box, they know only what the software does but do not know how the software does.This type of technique is valid for all the levels of testing where the specification exists.White box testingWhite box testing is a testing technique that evaluates the internal logic and structure of the code.In order to impement the white box testing, the testers should have the knowledge of coding so that they can deal with the internal code. They look into the internal code and finds out the unit which is malfunctioning.22) What is adhoc testing?Adhoc testing is an informal way of testing the software. It does not follow the formal process like requirement documents, test plan, test cases, etc.Characteristics of adhoc testing are:Adhoc testing is performed after the completion of formal testing on an application.The main aim of adhoc testing is to break the application without following any process.The testers who are executing the adhoc testing should have a deep knowledge of a product.23) How is monkey testing different from adhoc testing?Both monkey testing and adhoc testing follows the informal approach, but in monkey testing, we do not need to have deep knowledge of the software. However, to perform adhoc testing, testers should have a deep knowledge of the software.24) How is adhoc testing different from exploratory testing?The following is the list of differences between adhoc testing and exploratory testing:Adhoc testingExploratory testingAdhoc testing is the testing of software without any documentation or requirements specification.knowledge about the software while exploring the application.Documentation is not required.Documentation is mandatory in exploratory testing.The main aim of adhoc testing is to achieve perfection in testing.The main aim of exploratory testing is to learn the application.It is an informal approach.It is a formal approach.Adhoc testing does not require an expert testing engineer.Exploratory testing does not require an expert testing engineer.25) What are the different levels in software testing?There are four different levels in software testing:Unit/Component testingIntegration testingSystem testingAcceptance testingUnit testingIt is the lowest level in most of the models.Units are the programs or modules in the software.Unit testing is performed by the programmer that tests the modules, and if any bug is found, then it is fixed instantaneously.Integration testingIntegration means the combination of all the modules, and all these modules are tested as a group.Integration testing performs the testing on the data that flows from one module to another module.It basically checks the communication between two or more modules but not the functionality of individual modules.System testingSystem testing is used to test the complete or integrated system.It tests the software to ensure that it conforms the specified requirements specified in the SRS document.It is the final test and performs both functional and non-functional testing.Acceptance testingAcceptance testing is performed by the users or customers to check whether it meets their requirements or not.26) What is a bug life cycle?The bug life cycle is also known as the defect life cycle. Bug life cycle is a specific set of states that a bug goes through. The number of states that a defect goes through varies from project to project.NewWhen a new defect is logged and posted for the first time, then the status is assigned as New.AssignedOnce the bug is posted by the tester, the lead of the tester approves the bug and assigns the bug to the developing team.OpenThe developer starts analyzing and works on the defect fix.FixedWhen a developer makes a necessary code changes and verifies the change, then he/she can make the bug status as fixed.RetestTester does the retesting of the code at this stage to check whether the defect is fixed by the developer or not and change the status to retest.ReopenIf the bug persists even after the developer has fixed the bug, then tester changes the status to Reopen and once again bug goes through the bug life cycle.VerifiedThe tester retests the bug after it got fixed by the developer if no bug found then it changes the status to Verified.ClosedIf the bug is no longer exists, then it changes the status to Closed.DuplicateIf the defect is repeated twice or the defect corresponds to the same concept of the previous bug, then it changes the status to Duplicate.RejectedIf the developer feels that the defect is not a genuine defect, then it changes the status to Rejected.DeferredIf the bug is not of higher priority and can be solved in the next release, then the status changes to Deferred.
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A list of top frequently asked React Interview Questions and Answers are given below.General React Interview Questions1) What is React?React is a declarative, efficient, flexible open source front-end JavaScript library developed by Facebook in 2011. It follows the component-based approach for building reusable UI components, especially for single page application. It is used for developing interactive view layer of web and mobile apps. It was created by Jordan Walke, a software engineer at Facebook. It was initially deployed on Facebook's News Feed section in 2011 and later used in its products like WhatsApp & Instagram.For More Information, Click here.2) What are the features of React?React framework gaining quick popularity as the best framework among web developers. The main features of React are:Play VideoJSXComponentsOne-way Data BindingVirtual DOMSimplicityPerformanceFor More Information, Click here.3) What are the most crucial advantages of using React?Following is a list of the most crucial advantages of using React:React is easy to learn and useReact comes with good availability of documentation, tutorials, and training resources. It is easy for any developer to switch from JavaScript background to React and easily understand and start creating web apps using React. Anyone with little knowledge of JavaScript can start building web applications using React.React follows the MVC architecture.React is the V (view part) in the MVC (Model-View-Controller) architecture model and is referred to as "one of the JavaScript frameworks." It is not fully featured but has many advantages of the open-source JavaScript User Interface (UI) library, which helps execute the task in a better manner.React uses Virtual DOM to improve efficiency.React uses virtual DOM to render the view. The virtual DOM is a virtual representation of the real DOM. Each time the data changes in a react app, a new virtual DOM gets created. Creating a virtual DOM is much faster than rendering the UI inside the browser. Therefore, with the use of virtual DOM, the efficiency of the app improves. That's why React provides great efficiency.Creating dynamic web applications is easy.In React, creating a dynamic web application is much easier. It requires less coding and gives more functionality. It uses JSX (JavaScript Extension), which is a particular syntax letting HTML quotes and HTML tag syntax to render particular subcomponents.React is SEO-friendly.React facilitates a developer to develop an engaging user interface that can be easily navigated in various search engines. It also allows server-side rendering, which is also helpful to boost the SEO of your app.React allows reusable components.React web applications are made up of multiple components where each component has its logic and controls. These components provide a small, reusable piece of HTML code as an output that can be reused wherever you need them. The code reusability helps developers to make their apps easier to develop and maintain. It also makes the nesting of the components easy and allows developers to build complex applications of simple building blocks. The reuse of components also increases the pace of development.Support of handy toolsReact provides a lot of handy tools that can make the task of the developers understandable and easier. Use these tools in Chrome and Firefox dev extension, allowing us to inspect the React component hierarchies in the virtual DOM. It also allows us to select the particular components and examine and edit their current props and state.React has a rich set of libraries.React has a huge ecosystem of libraries and provides you the freedom to choose the tools, libraries, and architecture for developing the best application based on your requirement.Scope for testing the codesReact web applications are easy to test. These applications provide a scope where the developer can test and debug their codes with the help of native tools.For More Information, Click here.4) What are the biggest limitations of React?Following is the list of the biggest limitations of React:React is just a library. It is not a complete framework.It has a huge library which takes time to understand.It may be difficult for the new programmers to understand and code.React uses inline templating and JSX, which may be difficult and act as a barrier. It also makes the coding complex.5) What is JSX?JSX stands for JavaScript XML. It is a React extension which allows writing JavaScript code that looks similar to HTML. It makes HTML file easy to understand. The JSX file makes the React application robust and boosts its performance. JSX provides you to write XML-like syntax in the same file where you write JavaScript code, and then preprocessor (i.e., transpilers like Babel) transform these expressions into actual JavaScript code. Just like XML/HTML, JSX tags have a tag name, attributes, and children.Exampleclass App extends React.Component { render() { return( Hello JavaTpoint ) } } In the above example, text inside tag return as JavaScript function to the render function. After compilation, the JSX expression becomes a normal JavaScript function, as shown below.React.createElement("h1", null, "Hello JavaTpoint"); For More Information, Click here.6) Why can't browsers read JSX?Browsers cannot read JSX directly because they can only understand JavaScript objects, and JSX is not a regular JavaScript object. Thus, we need to transform the JSX file into a JavaScript object using transpilers like Babel and then pass it to the browser.7) Why we use JSX?It is faster than regular JavaScript because it performs optimization while translating the code to JavaScript.Instead of separating technologies by putting markup and logic in separate files, React uses components that contain both.t is type-safe, and most of the errors can be found at compilation time.It makes easier to create templates.8) What do you understand by Virtual DOM?A Virtual DOM is a lightweight JavaScript object which is an in-memory representation of real DOM. It is an intermediary step between the render function being called and the displaying of elements on the screen. It is similar to a node tree which lists the elements, their attributes, and content as objects and their properties. The render function creates a node tree of the React components and then updates this node tree in response to the mutations in the data model caused by various actions done by the user or by the system.9) Explain the working of Virtual DOM.Virtual DOM works in three steps:1. Whenever any data changes in the React App, the entire UI is re-rendered in Virtual DOM representation.2. Now, the difference between the previous DOM representation and the new DOM is calculated.3. Once the calculations are completed, the real DOM updated with only those things which are changed.10) How is React different from Angular?The React is different from Angular in the following ways.AngularReactAuthorGoogleFacebook CommunityDeveloperMisko HeveryJordan WalkeInitial ReleaseOctober 2010March 2013LanguageJavaScript, HTMLJSXTypeOpen Source MVC FrameworkOpen Source JS FrameworkRenderingClient-SideServer-SideData-BindingBi-directionalUni-directionalDOMRegular DOMVirtual DOMTestingUnit and Integration TestingUnit TestingApp ArchitectureMVCFluxPerformanceSlowFast, due to virtual DOM.For More Information, Click here.11) How React's ES6 syntax is different from ES5 syntax?The React's ES6 syntax has changed from ES5 syntax in the following aspects.require vs. Import// ES5 var React = require('react'); // ES6 import React from 'react'; exports vs. export// ES5 module.exports = Component; // ES6 export default Component; component and function// ES5 var MyComponent = React.createClass({ render: function() { return( Hello JavaTpoint ); } }); // ES6 class MyComponent extends React.Component { render() { return( Hello Javatpoint ); } } props// ES5 var App = React.createClass({ propTypes: { name: React.PropTypes.string }, render: function() { return( Hello, {this.props.name}! ); } }); // ES6 class App extends React.Component { render() { return( Hello, {this.props.name}! ); } } statevar App = React.createClass({ getInitialState: function() { return { name: 'world' }; }, render: function() { return( Hello, {this.state.name}! ); } }); // ES6 class App extends React.Component { constructor() { super(); this.state = { name: 'world' }; } render() { return( Hello, {this.state.name}! ); } } 12) What is the difference between ReactJS and React Native?The main differences between ReactJS and React Native are given below.SNReactJSReact Native1.Initial release in 2013.Initial release in 2015.2.It is used for developing web applications.It is used for developing mobile applications.3.It can be executed on all platforms.It is not platform independent. It takes more effort to be executed on all platforms.4.It uses a JavaScript library and CSS for animations.It comes with built-in animation libraries.5.It uses React-router for navigating web pages.It has built-in Navigator library for navigating mobile applications.6.It uses HTML tags.It does not use HTML tags.7.In this, the Virtual DOM renders the browser code.In this, Native uses its API to render code for mobile applications.For More Information, Click here.13) What is the difference between Real DOM and Virtual DOM?The following table specifies the key differences between the Real DOM and Virtual DOM:The real DOM creates a new DOM if the element updates.Real DOMVirtual DOMThe real DOM updates slower.The virtual DOM updates faster.The real DOM can directly update HTML.The virtual DOM cannot directly update HTML.The virtual DOM updates the JSX if the element updates.In real DOM, DOM manipulation is very expensive.In virtual DOM, DOM manipulation is very easy.There is a lot of memory wastage in The real DOM.There is no memory wastage in the virtual DOM.React Component Interview Questions14) What do you understand from "In React, everything is a component."In React, components are the building blocks of React applications. These components divide the entire React application's UI into small, independent, and reusable pieces of code. React renders each of these components independently without affecting the rest of the application UI. Hence, we can say that, in React, everything is a component.15) Explain the purpose of render() in React.It is mandatory for each React component to have a render() function. Render function is used to return the HTML which you want to display in a component. If you need to rendered more than one HTML element, you need to grouped together inside single enclosing tag (parent tag) such as , , etc. This function returns the same result each time it is invoked.Example: If you need to display a heading, you can do this as below.import React from 'react' class App extends React.Component { render (){ return ( Hello World ) } } export default App Points to Note:Each render() function contains a return statement.The return statement can have only one parent HTML tag.16) How can you embed two or more components into one?You can embed two or more components into the following way:import React from 'react' class App extends React.Component { render (){ return ( Hello World ) } } class Example extends React.Component { render (){ return ( Hello JavaTpoint ) } } export default App 17) What is Props?Props stand for "Properties" in React. They are read-only inputs to components. Props are an object which stores the value of attributes of a tag and work similar to the HTML attributes. It gives a way to pass data from the parent to the child components throughout the application.It is similar to function arguments and passed to the component in the same way as arguments passed in a function.Props are immutable so we cannot modify the props from inside the component. Inside the components, we can add attributes called props. These attributes are available in the component as this.props and can be used to render dynamic data in our render method.For More Information, Click here.18) What is a State in React?The State is an updatable structure which holds the data and information about the component. It may be changed over the lifetime of the component in response to user action or system event. It is the heart of the react component which determines the behavior of the component and how it will render. It must be kept as simple as possible.Let's create a "User" component with "message state."import React from 'react' class User extends React.Component { constructor(props) { super(props) this.state = { message: 'Welcome to JavaTpoint' } } render() { return ( {this.state.message} ) } } export default User For More Information, Click here.19) Differentiate between States and Props.The major differences between States and Props are given below.SNPropsState1.Props are read-only.State changes can be asynchronous.2.Props are immutable.State is mutable.3.Props allow you to pass data from one component to other components as an argument.State holds information about the components.4.Props can be accessed by the child component.State cannot be accessed by child components.5.Props are used to communicate between components.States can be used for rendering dynamic changes with the component.6.The stateless component can have Props.The stateless components cannot have State.7.Props make components reusable.The State cannot make components reusable.8.Props are external and controlled by whatever renders the component.The State is internal and controlled by the component itself.For More Information, Click here.20) How can you update the State of a component?We can update the State of a component using this.setState() method. This method does not always replace the State immediately. Instead, it only adds changes to the original State. It is a primary method which is used to update the user interface(UI) in response to event handlers and server responses.Exampleimport React, { Component } from 'react'; import PropTypes from 'prop-types'; class App extends React.Component { constructor() { super(); this.state = { msg: "Welcome to JavaTpoint" }; this.updateSetState = this.updateSetState.bind(this); } updateSetState() { this.setState({ msg:"Its a best ReactJS tutorial" }); } render() { return ( {this.state.msg} ) functions.//General way render() { return( ); } 23) What is an event in React?An event is an action which triggers as a result of the user action or system generated event like a mouse click, loading of a web page, pressing a key, window resizes, etc. In React, the event handling system is very similar to handling events in DOM elements. The React event handling system is known as Synthetic Event, which is a cross-browser wrapper of the browser's native event.Handling events with React have some syntactical differences, which are:React events are named as camelCase instead of lowercase.With JSX, a function is passed as the event handler instead of a string.For More Information, Click here.24) How do you create an event in React?We can create an event as follows.class Display extends React.Component({ show(msgEvent) { // code }, render() { // Here, we render the div with an onClick prop return ( 31) Explain the lifecycle methods of React components in detail.The important React lifecycle methods are:getInitialState(): It is used to specify the default value of this.state. It is executed before the creation of the component.componentWillMount(): It is executed before a component gets rendered into the DOM.componentDidMount(): It is executed when the component gets rendered and placed on the DOM. Now, you can do any DOM querying operations.componentWillReceiveProps(): It is invoked when a component receives new props from the parent class and before another render is called. If you want to update the State in response to prop changes, you should compare this.props and nextProps to perform State transition by using this.setState() method.shouldComponentUpdate(): It is invoked when a component decides any changes/updation to the DOM and returns true or false value based on certain conditions. If this method returns true, the component will update. Otherwise, the component will skip the updating.componentWillUpdate(): It is invoked before rendering takes place in the DOM. Here, you can't change the component State by invoking this.setState() method. It will not be called, if shouldComponentUpdate() returns false.componentDidUpdate(): It is invoked immediately after rendering takes place. In this method, you can put any code inside this which you want to execute once the updating occurs.componentWillUnmount(): It is invoked immediately before a component is destroyed and unmounted permanently. It is used to clear up the memory spaces such as invalidating timers, event listener, canceling network requests, or cleaning up DOM elements. If a component instance is unmounted, you cannot mount it again.For More Information, Click here.32) What are Pure Components?Pure components introduced in React 15.3 version. The React.Component and React.PureComponent differ in the shouldComponentUpdate() React lifecycle method. This method decides the re-rendering of the component by returning a boolean value (true or false). In React.Component, shouldComponentUpdate() method returns true by default. But in React.PureComponent, it compares the changes in state or props to re-render the component. The pure component enhances the simplicity of the code and performance of the application.33) What are Higher Order Components(HOC)?In React, Higher Order Component is an advanced technique for reusing component logic. It is a function that takes a component and returns a new component. In other words, it is a function which accepts another function as an argument. According to the official website, it is not the feature(part) in React API, but a pattern that emerges from React's compositional nature.For More Information, Click here.34) What can you do with HOC?You can do many tasks with HOC, some of them are given below:Code ReusabilityProps manipulationState manipulationRender highjacking35) What is the difference between Element and Component?The main differences between Elements and Components are:SNElementComponent1.An element is a plain JavaScript object which describes the component state and DOM node, and its desired properties.A component is the core building block of React application. It is a class or function which accepts an input and returns a React element.2.It only holds information about the component type, its properties, and any child elements inside it.It can contain state and props and has access to the React lifecycle methods.3.It is immutable.It is mutable.4.We cannot apply any methods on elements.We can apply methods on components.5.Example:const element = React.createElement('div',{id: 'login-btn'},'Login')Example:function Button ({ onLogin }) {return React.createElement('div',{id: 'login-btn', onClick: onLogin},'Login')}36) How to write comments in React?In React, we can write comments as we write comments in JavaScript. It can be in two ways:1. Single Line Comments: We can write comments as /* Block Comments */ with curly braces:{/* Single Line comment */} 2. Multiline Comments: If we want to comment more that one line, we can do this as{ /* Multi line comment */ } 37) Why is it necessary to start component names with a capital letter?In React, it is necessary to start component names with a capital letter. If we start the component name with lower case, it will throw an error as an unrecognized tag. It is because, in JSX, lower case tag names are considered as HTML tags.38) What are fragments?In was introduced in React 16.2 version. In React, Fragments are used for components to return multiple elements. It allows you to group a list of multiple children without adding an extra node to the DOM.Examplerender() { return ( ) } There is also a shorthand syntax exists for declaring Fragments, but it's not supported in many tools:render() { return ( ) } For More Information, Click here.39) Why are fragments better than container divs?Fragments are faster and consume less memory because it did not create an extra DOM node.Some CSS styling like CSS Grid and Flexbox have a special parent-child relationship and add tags in the middle, which makes it hard to keep the desired layout.The DOM Inspector is less cluttered.40) How to apply validation on props in React?Props validation is a tool which helps the developers to avoid future bugs and problems. It makes your code more readable. React components used special property PropTypes that help you to catch bugs by validating data types of values passed through props, although it is not necessary to define components with propTypes.We can apply validation on props using App.propTypes in React component. When some of the props are passed with an invalid type, you will get the warnings on JavaScript console. After specifying the validation patterns, you need to set the App.defaultProps.class App extends React.Component { render() {} } Component.propTypes = { /*Definition */}; For More Information, Click here.41) What is create-react-app?Create React App is a tool introduced by Facebook to build React applications. It provides you to create single-page React applications. The create-react-app are preconfigured, which saves you from time-consuming setup and configuration like Webpack or Babel. You need to run a single command to start the React project, which is given below.$ npx create-react-app my-app This command includes everything which we need to build a React app. Some of them are given below:It includes React, JSX, ES6, and Flow syntax support.It includes Autoprefixed CSS, so you don't need -webkit- or other prefixes.It includes a fast, interactive unit test runner with built-in support for coverage reporting.It includes a live development server that warns about common mistakes.It includes a build script to bundle JS, CSS, and images for production, with hashes and source maps.For More Information, Click here.42) How can you create a component in React?There are two possible ways to create a component in React:Function Components: This is the simplest way to create a component in React. These are the pure JavaScript functions that accept props object as the first parameter and return React elements:function Greeting({ message }) { return {`Hello, ${message}`}h1> } Class Components: The class components method facilitates you to use ES6 class to define a component. The above function component can be written as:class Greeting extends React.Component { render() { return {`Hello, ${this.props.message}`}h1> } } 43) When do we prefer to use a class component over a function component?If a component needs state or lifecycle methods, we should use the class component; otherwise, use the function component. However, after React 16.8, with the addition of Hooks, you could use state, lifecycle methods, and other features that were only available in the class component right in your function component.44) Is it possible for a web browser to read JSX directly?Web browsers can't read JSX directly. This is because the web browsers are built to read the regular JS objects only, and JSX is not a regular JavaScript object.If you want a web browser to read a JSX file, you must transform the files into a regular JavaScript object. For this purpose, Babel is used.45) What do you understand by the state in React?In react, the state of a component is an object that holds some information that may change over the component's lifetime. It would be best to try to make your state as simple as possible and minimize the number of stateful components.Let's see how to create a user component with message state:class User extends React.Component { constructor(props) { super(props) this.state = { message: 'Welcome to React world' } } render() { return ( {this.state.message}h1> div> ) } } The state is very similar to props, but it is private and fully controlled by the component. i.e., It is not accessible to any other component till the owner component decides to pass it.46) What are the main changes that appear in React's ES6 syntax compared to ES5 syntax?/How different is React's ES6 syntax compared to ES5?Following are the most visible syntax we can see while comparing ES6 and ES5:require vs importSyntax in ES5:var React = require('react'); Syntax in ES6:import React from 'react'; export vs exportsSyntax in ES5:module.exports = Component; Syntax in ES6:export default Component; component and functionSyntax in ES5:var MyComponent = React.createClass({ render: function() { return Hello JavaTpoint!h3> ; } }); Syntax in ES6:class MyComponent extends React.Component { render() { return Hello JavaTpoint!h3> ; } } propsSyntax in ES5:var App = React.createClass({ propTypes: { name: React.PropTypes.string }, render: function() { return Hello, {this.props.name}!h3> ; } }); Syntax in ES6:class App extends React.Component { render() { return Hello, {this.props.name}!h3> ; } } stateSyntax in ES5:var App = React.createClass({ getInitialState: function() { return { name: 'world' }; }, render: function() { return Hello, {this.state.name}!h3> ; } }); Syntax in ES6:class App extends React.Component { constructor() { super(); this.state = { name: 'world' }; } render() { return Hello, {this.state.name}!h3> ; } } 47) What do you understand by props in React?In React, the props are inputs to components. They are single values or objects containing a set of values passed to components on creation using a naming convention similar to HTML-tag attributes. They are data passed down from a parent component to a child component.The main purpose of props in React is to provide the following component functionality:Pass custom data to your component.Trigger state changes.Use via this.props.reactProp inside component's render() method.For example, let us create an element with reactProp property: This reactProp name becomes a property attached to React's native props object, which already exists on all React library components.props.reactProp React Refs Interview Questions48) What do you understand by refs in React?Refs is the shorthand used for references in React. It is an attribute which helps to store a reference to particular DOM nodes or React elements. It provides a way to access React DOM nodes or React elements and how to interact with it. It is used when we want to change the value of a child component, without making the use of props.For More Information, Click here.49) How to create refs?Refs can be created by using React.createRef() and attached to React elements via the ref attribute. It is commonly assigned to an instance property when a component is created, and then can be referenced throughout the component.class MyComponent extends React.Component { constructor(props) { super(props); this.callRef = React.createRef(); } render() { return this.callRef} />; ( { e.preventDefault(); console.log(inputRef.current.value); }; render() { return ( this.handleSubmit(e)}> Submit ); } } export default App; For More Information, Click here.51) Which is the preferred option callback refs or findDOMNode()?The preferred option is to use callback refs over findDOMNode() API. Because callback refs give better control when the refs are set and unset whereas findDOMNode() prevents certain improvements in React in the future.class MyComponent extends Component { componentDidMount() { findDOMNode(this).scrollIntoView() } render() { return } } The recommended approach is:class MyComponent extends Component { componentDidMount() { this.node.scrollIntoView() } render() { return this.node = node} /> } } class MyComponent extends Component { componentDidMount() { this.node.scrollIntoView() } render() { return this.node = node} /> } } 52) What is the use of Refs?The Ref in React is used in the following cases:It is used to return a reference to the element.It is used when we need DOM measurements such as managing focus, text selection, or media playback.It is used in triggering imperative animations.It is used when integrating with third-party DOM libraries.It can also use as in callbacks.For More Information, Click here.React Router Interview Questions53) What is React Router?React Router is a standard routing library system built on top of the React. It is used to create Routing in the React application using React Router Package. It helps you to define multiple routes in the app. It provides the synchronous URL on the browser with data that will be displayed on the web page. It maintains the standard structure and behavior of the application and mainly used for developing single page web applications.For More Information, Click here.54) Why do we need a Router in React?React Router plays an important role to display multiple views in a single page application. It is used to define multiple routes in the app. When a user types a specific URL into the browser, and if this URL path matches any 'route' inside the router file, the user will be redirected to that particular Route. So, we need to add a Router library to the React app, which allows creating multiple routes with each leading to us a unique view. React Router Example switch Click on this button ); } 64) What are the rules you should follow for the hooks in React?We have to follow the following two rules to use hooks in React:You should call hooks only at the top level of your React functions and not inside the loops, conditions, or nested functions. This is used to ensure that hooks are called in the same order each time a component renders, and it also preserves the state of hooks between multiple useState and useEffect calls.You should call hooks from React functions only. Don't call hooks from regular JavaScript functions.65) What are forms in React?In React, forms are used to enable users to interact with web applications. Following is a list of the most common usage of forms in React:Forms facilitate users to interact with the application. By using forms, the users can communicate with the application and enter the required information whenever required.Forms contain certain elements, such as text fields, buttons, checkboxes, radio buttons, etc., that can make the application more interactive and beautiful.Forms are the best possible way to take inputs from the users.Forms are used for many different tasks such as user authentication, searching, filtering, indexing, etc.66) What is an error boundary or error boundaries?An error boundary is a concept introduced in version 16 of React. Error boundaries provide a way to find out the errors that occur in the render phase. Any component which uses one of the following lifecycle methods is considered an error boundary. Let's see the places where an error boundary can detect an error:Render phaseInside a lifecycle methodInside the constructorLet's see an example to understand it better:Without using error boundaries:class CounterComponent extends React.Component{ constructor(props){ super(props); this.state = { counterValue: 0 } this.incrementCounter = this.incrementCounter.bind(this); } incrementCounter(){ this.setState(prevState => counterValue = prevState+1); } render(){ if(this.state.counter === 2){ throw new Error('Crashed'); } return( 67) In which cases do error boundaries not catch errors?Following are some cases in which error boundaries don't catch errors:Error boundaries don't catch errors inside the event handlers.During the server-side rendering.In the case when errors are thrown in the error boundary code itself.Asynchronous code using setTimeout or requestAnimationFrame callbacks.React Redux Interview Questions68) What were the major problems with MVC framework?The major problems with the MVC framework are:DOM manipulation was very expensive.It makes the application slow and inefficient.There was a huge memory wastage.It makes the application debugging hard.69) Explain the Flux concept.Flux is an application architecture that Facebook uses internally for building the client-side web application with React. It is neither a library nor a framework. It is a kind of architecture that complements React as view and follows the concept of Unidirectional Data Flow model. It is useful when the project has dynamic data, and we need to keep the data updated in an effective manner.For More Information, Click here.70) What is Redux?Redux is an open-source JavaScript library used to manage application state. React uses Redux for building the user interface. The Redux application is easy to test and can run in different environments showing consistent behavior. It was first introduced by Dan Abramov and Andrew Clark in 2015.React Redux is the official React binding for Redux. It allows React components to read data from a Redux Store, and dispatch Actions to the Store to update data. Redux helps apps to scale by providing a sensible way to manage state through a unidirectional data flow model. React Redux is conceptually simple. It subscribes to the Redux store, checks to see if the data which your component wants have changed, and re-renders your component.For More Information, Click here.71) What are the three principles that Redux follows?The three principles that redux follows are:Single source of truth: The State of your entire application is stored in an object/state tree inside a single Store. The single State tree makes it easier to keep changes over time. It also makes it easier to debug or inspect the application.The State is read-only: There is only one way to change the State is to emit an action, an object describing what happened. This principle ensures that neither the views nor the network callbacks can write directly to the State.Changes are made with pure functions: To specify how actions transform the state tree, you need to write reducers (pure functions). Pure functions take the previous State and Action as a parameter and return a new State.72) List down the components of Redux.The components of Redux are given below.STORE: A Store is a place where the entire State of your application lists. It is like a brain responsible for all moving parts in Redux.ACTION: It is an object which describes what happened.REDUCER: It determines how the State will change.For More Information, Click here.73) Explain the role of Reducer.Reducers read the payloads from the actions and then updates the Store via the State accordingly. It is a pure function which returns a new state from the initial State. It returns the previous State as it is if no work needs to be done.74) What is the significance of Store in Redux?A Store is an object which holds the application's State and provides methods to access the State, dispatch Actions and register listeners via subscribe(listener). The entire State tree of an application is saved in a single Store which makes the Redux simple and predictable. We can pass middleware to the Store which handles the processing of data as well as keep a log of various actions that change the Store's State. All the Actions return a new state via reducers.75) How is Redux different from Flux?The Redux is different from Flux in the following manner.SNReduxFlux1.Redux is an open-source JavaScript library used to manage application State.Flux is neither a library nor a framework. It is a kind of architecture that complements React as view and follows the concept of Unidirectional Data Flow model.2.Store's State is immutable.Store's State is mutable.3.In this, Store and change logic are separate.In this, the Store contains State and change logic.4.It has only a single Store.It can have multiple Store.5.Redux does not have Dispatcher concept.It has single Dispatcher, and all actions pass through that Dispatcher.76) What are the advantages of Redux?The main advantages of React Redux are:React Redux is the official UI bindings for react Application. It is kept up-to-date with any API changes to ensure that your React components behave as expected.It encourages good 'React' architecture.It implements many performance optimizations internally, which allows to components re-render only when it actually needs.It makes the code maintenance easy.Redux's code written as functions which are small, pure, and isolated, which makes the code testable and independent.77) How to access the Redux store outside a component?You need to export the Store from the module where it created with createStore() method. Also, you need to assure that it will not pollute the global window space.store = createStore(myReducer) export default store Some Most Frequently Asked React MCQ1) What is Babel in React?Babel is a transpiler.Babel is an interpreter.Babel is a compiler.Babel is both a compiler and a transpiler.Show Answer Workspace2) What do you understand by the Reconciliation process in React?The Reconciliation process is a process through which React updates the DOM.The Reconciliation process is a process through which React deletes the DOM.The Reconciliation process is a process through which React updates and deletes the component.It is a process to set the state.Show Answer Workspace3) Which of the following is used to pass data to a component from outside React applications?setStatepropsrender with argumentsPropTypesShow Answer Workspace4) Which of the following function allows you to render React content on an HTML page?React.mount()React.start()React.render()React.render()Show Answer Workspace5) Which of the following shows the correct phases of the component lifecycle?Mounting: getDerivedStateFromProps(); Updating: componentWillUnmount(); Unmounting: shouldComponentUpdate()Mounting: componentWillUnmount(); Updating: render(); Unmounting: setState()Mounting: componentDidMount(); Updating: componentDidUpdate(); Unmounting: componentWillUnmount()Mounting: constructor(); Updating: getDerivedStateFromProps(); Unmounting: render()Show Answer Workspace6) In MVC (Model, View, Controller) model, how can you specify the role of the React?React is the Middleware in MVC.React is the Controller in MVC.React is the Model in MVC.React is the Router in MVC.Show Answer Workspace7) Which of the following is the most precise difference between Controlled Component and Uncontrolled Component?In controlled components, every state mutation will have an associated handler function. On the other hand, the uncontrolled components store their states internally.The controlled components store their states internally, while in the uncontrolled components, every state mutation will have an associated handler function.The controlled component is good at controlling itself, while the uncontrolled component has no idea how to control itself.Every state mutation does not have an associated handler function in controlled components, while the uncontrolled components do not store their states internally.Show Answer Workspace8) What do the arbitrary inputs of components in React are called?KeysPropsElementsRefShow Answer Workspace9) What do you understand by the "key" prop in React?"Key" prop is used to look pretty, and there is no benefit whatsoever."Key" prop is a way for React to identify a newly added item in a list and compare it during the "diffing" algorithm."Key" prop is one of the attributes in HTML."Key" prop is NOT commonly used in the array.Show Answer Workspace10) Which of the following is the correct data flow sequence of flux concept in React?Action->Dispatcher->View->StoreAction->Dispatcher->Store->ViewAction->Store->Dispatcher->ViewNone of the above.Show Answer Workspace
More detailsPublished - Tue, 06 Dec 2022
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1) What is GIT?Git is an open source distributed version control system and source code management (SCM) system with an insistence to control small and large projects with speed and efficiency.2) Which language is used in Git?Git uses 'C' language. Git is quick, and 'C' language makes this possible by decreasing the overhead of run times contained with high-level languages.3) What is a repository in Git?A repository consists of a list named .git, where git holds all of its metadata for the catalog. The content of the .git file is private to Git.4) What is 'bare repository' in Git?A "bare" repository in Git includes the version control information and no working files (no tree), and it doesn?t include the special. git sub-directory. Instead, it consists of all the contents of the .git sub-directory directly in the main directory itself, whereas working list comprises of:Play VideoxA .git subdirectory with all the Git associated revision history of your repo.A working tree, or find out copies of your project files.5) What is the purpose of GIT stash?GIT stash takes the present state of the working file and index and puts in on the stack for next and gives you back a clean working file. So in case if you are in the middle of object and require to jump over to the other task, and at the same time you don't want to lose your current edits, you can use GIT stash.6) What is GIT stash drop?When you are done with the stashed element or want to delete it from the directory, run the git 'stash drop' command. It will delete the last added stash item by default, and it can also remove a specific topic if you include as an argument.7) What are the advantages of using GIT?Here are some of the essential advantages of Git:Data repetition and data replication is possibleIt is a much applicable serviceFor one depository you can have only one directory of GitThe network performance and disk application are excellentIt is effortless to collaborate on any projectYou can work on any plan within the Git8) What is the function of 'GIT PUSH' in GIT?'GIT PUSH' updates remote refs along with related objects9) Why do we require branching in GIT?With the help of branching, you can keep your branch, and you can also jump between the different branches. You can go to your past work while at the same time keeping your recent work intact.10) What is the purpose of 'git config'?The 'Git config' is a great method to configure your choice for the Git installation. Using this command, you can describe the repository behavior, preferences, and user information.11) What is the definition of "Index" or "Staging Area" in GIT?When you are making the commits, you can make innovation to it, format it and review it in the common area known as 'Staging Area' or 'Index'.12) What is a 'conflict' in git?A 'conflict' appears when the commit that has to be combined has some change in one place, and the current act also has a change at the same place. Git will not be easy to predict which change should take precedence.13) What is the difference between git pull and git fetch?Git pull command pulls innovation or commits from a specific branch from your central repository and updates your object branch in your local repository.Git fetch is also used for the same objective, but it works in a slightly different method. When you behave a git fetch, it pulls all new commits from the desired branch and saves it in a new branch in your local repository. If you need to reflect these changes in your target branch, git fetch should be followed with a git merge. Your target branch will only be restored after combining the target branch and fetched branch. To make it simple for you, remember the equation below:Git pull = git fetch + git merge14) How to resolve a conflict in Git?If you need to resolve a conflict in Git, edit the list for fixing the different changes, and then you can run "git add" to add the resolved directory, and after that, you can run the 'git commit' for committing the repaired merge.15) What is the purpose of the git clone?The git clone command generates a copy of a current Git repository. To get the copy of a central repository, 'cloning' is the simplest way used by programmers.16) What is git pull origin?pull is a get and a consolidation. 'git pull origin master' brings submits from the master branch of the source remote (into the local origin/master branch), and then it combines origin/master into the branch you currently have looked out.17) What does git commit a?Git commits "records changes to the storehouse" while git push " updates remote refs along with contained objects" So the first one is used in a network with your local repository, while the latter one is used to communicate with a remote repository.18) Why GIT better than Subversion?GIT is an open source version control framework; it will enable you to run 'adaptations' of a task, which demonstrate the changes that were made to the code over time also it allows you keep the backtrack if vital and fix those changes. Multiple developers can check out, and transfer changes, and each change can then be attributed to a particular developer.19) Explain what is commit message?Commit message is a component of git which shows up when you submit a change. Git gives you a content tool where you can enter the adjustments made to a commit.20) Why is it desirable to create an additional commit rather than amending an existing commit?There are couples of reasonThe correct activity will devastate the express that was recently saved in a commit. If only the commit message gets changed, that's not a problem. But if the contents are being modified, chances of excluding something important remains more.Abusing "git commit- amends" can cause a small commit to increase and acquire inappropriate changes.21) What does 'hooks' comprise of in Git?This index comprises of Shell contents which are enacted after running the relating git commands. For instance, Git will attempt to execute the post-commit content after you run a commit.22) What is the distinction between Git and Github?A) Git is a correction control framework, a tool to deal with your source code history.GitHub is a hosting function for Git storehouses.GitHub is a website where you can transfer a duplicate of your Git archive. It is a Git repository hosting service, which offers the majority of the distributed update control and source code management (SCM) usefulness of Git just as including its features.23) In Git, how would you return a commit that has just been pushed and made open?There can be two answers to this question and ensure that you incorporate both because any of the below choices can be utilized relying upon the circumstance:Remove or fix the bad document in another commit and push it to the remote repository. This is a unique approach to correct a mistake. Once you have necessary changes to the record, commit it to the remote repository for that I will utilizegit submit - m "commit message."Make another commit that fixes all changes that were made in the terrible commit. to do this, I will utilize a commandgit revert 24) What does the committed item contain?Commit item contains the following parts; you should specify all the three present below:A set of records, representing to the condition of a task at a given purpose of timeReferences to parent commit objectsAn SHAI name, a 40 character string that uniquely distinguishes the commit object.25) Describing branching systems you have utilized?This question is a challenge to test your branching knowledge with Git along these lines, inform them regarding how you have utilized branching in your past activity and what reason does it serves, you can refer the below mention points:Feature Branching:A component branch model keeps the majority of the changes for a specific element within a branch. At the point when the item is throughout tested and approved by automated tests, the branch is then converged into master.Task BranchingIn this model, each assignment is actualized on its branch with the undertaking key included in the branch name. It is anything but difficult to see which code actualizes which task, search for the task key in the branch name.Release BranchingOnce the create branch has procured enough features for a discharge, you can clone that branch to frame a Release branch. Making this branch begins the following discharge cycle so that no new features can be included after this point, just bug fixes, documentation age, and other release oriented assignments ought to go in this branch. When it is prepared to deliver, the release gets converged into master and labeled with a form number. Likewise, it should be converged once again into creating a branch, which may have advanced since the release was started.At last, disclose to them that branching methodologies fluctuate starting with one association then onto the next, so I realize essential branching activities like delete, merge, checking out a branch, etc.26) By what method will you know in Git if a branch has just been combined into master?The appropriate response is immediate.To know whether a branch has been merged into master or not you can utilize the below commands:git branch - merged It records the branches that have been merged into the present branch.git branch - no merged It records the branches that have not been merged.27) How might you fix a messed up submit?To fix any messed up commit, you will utilize the order "git commit?correct." By running this direction, you can set the wrecked commit message in the editor.28) Mention the various Git repository hosting functions.The following are the Git repository hosting functions:PikacodeVisual Studio OnlineGitHubGitEnterpriseSourceForge.net29) Mention some of the best graphical GIT customers for LINUX?Some of the best GIT customer for LINUX isGit ColaSmart gitGit-gGit GUIGiggleqGit30) What is Subgit? Why use it?'Subgit' is a tool that migrates SVN to Git. It is a stable and stress-free migration. Subgit is one of the solutions for a company-wide migration from SVN to Git that is:It is much superior to git-svnNo need to change the infrastructure that is already placed.It allows using all git and all sub-version features.It provides stress ?free migration experience.
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