Frequently asked .NET interview questions - 2023 (updated)

 

1. What is .NET architecture?
   .NET architecture is a collection of technologies that provide an infrastructure for developing Windows and web applications, which includes languages, libraries, frameworks, and tools.
2. What is the difference between .NET Framework and .NET Core?
   .NET Framework is a full-featured development platform that runs only on Windows, while .NET Core is a modular, open-source, cross-platform development framework that can run on Windows, Linux, and macOS.
3. What are the different types of .NET applications?
   The different types of .NET applications include Windows Forms, Web Forms, Console Applications, ASP.NET, and Windows Services.
4. What is the Common Language Runtime (CLR)?
   The Common Language Runtime (CLR) is the runtime environment in .NET that manages the execution of code and provides services such as memory management, garbage collection, exception handling, and security.
5. What is managed code?
    Managed code is code that is executed by the CLR, which provides services such as memory management, garbage collection, and exception handling.
6. What is an assembly in .NET?
    An assembly is a self-contained unit of code that contains metadata about the types, methods, and other elements in the code, as well as the IL code itself.
7. What is the Global Assembly Cache (GAC)??

The Global Assembly Cache (GAC) is a machine-wide repository for .NET assemblies that are intended to be shared across multiple applications.

8. What is Reflection in .NET?
    Reflection is a feature in .NET that allows you to inspect and manipulate the metadata of types and objects at runtime.
9. What is the difference between Early binding and Late binding in .NET?
    Early binding is when the type of an object is known at compile time, while Late binding is when the type of an object is determined at runtime.
10. What is the difference between Abstract class and Interface in .NET?
     An abstract class can contain both abstract and non-abstract methods, while an interface can only contain method signatures. An abstract class can also have fields and constructors, while an interface cannot.
11. What is the difference between Static class and Singleton class in .NET?
     A static class is a class that cannot be instantiated, while a singleton class is a class that can only have one instance created.
12. What is the difference between Boxing and Unboxing in .NET?
     Boxing is the process of converting a value type to a reference type, while unboxing is the process of converting a reference type back to a value type.
13. What is the difference between a Thread and a Process in .NET?
     A thread is a unit of execution within a process, while a process is a separate instance of a program that runs independently of other processes.
14. What is a Delegate in .NET?
     A delegate is a type that represents a reference to a method with a particular signature, which can be used to call that method or pass it as a parameter.
15. What is a Lambda Expression in .NET?
     A lambda expression is a concise way of defining an anonymous function that can be used to pass a function as a parameter or assign it to a variable.
16. What is an Extension Method in .NET?
     An extension method is a static method that can be used to add new functionality to existing types without modifying the original type.
17. What is an Attribute in .NET?
     An attribute is a declarative tag that can be applied to various elements in code to provide additional information about that element.

 

18.  What is the difference between IEnumerable and IQueryable in .NET?
The main difference between IEnumerable and IQueryable is in how they handle queries. When you execute a query against an IEnumerable collection, the query is performed locally in memory, meaning that all the data in the collection is loaded into memory and processed on the client-side. This can be inefficient for large collections, and can result in poor performance.

In summary, IEnumerable is a simple interface that represents a non-generic collection, while IQueryable extends IEnumerable and provides a set of query operators that can be used to efficiently query data sources. The main difference between the two is that IQueryable allows for more efficient queries by performing the query on the data source itself, and supports deferred execution of queries.

19.   What is LINQ in .NET?
 LINQ (Language Integrated Query) is a set of technologies in .NET that provide a unified approach to querying data from different data sources using a common syntax.

19.  What is ASP.NET MVC?
 ASP.NET MVC (Model-View-Controller) is a web application framework in .NET that separates an application into three main components: the model (data), the view (UI), and the controller (logic).

20.  What is Web API in .NET?
 Web API is a framework in .NET that allows you to build RESTful web services that can be consumed by different clients, such as web applications or mobile apps.

21.  What is Entity Framework in .NET?
 Entity Framework is an ORM (Object-Relational Mapping) framework in .NET that allows you to interact with databases using a high-level object-oriented interface, without writing SQL queries.

22.  What is ADO.NET in .NET?
 ADO.NET (ActiveX Data Objects .NET) is a set of technologies in .NET that provide a way to access and manipulate data from different data sources, such as databases or XML files.

23.  What is WCF in .NET?
 WCF (Windows Communication Foundation) is a framework in .NET that allows you to build distributed systems using different communication protocols, such as HTTP, TCP, or MSMQ.

24.  What is the difference between REST and SOAP?
 REST (Representational State Transfer) is an architectural style that uses HTTP verbs and URLs to represent resources, while SOAP (Simple Object Access Protocol) is a protocol that uses XML messages and can use different transport protocols.

25.  What is the purpose of IIS in .NET?
 IIS (Internet Information Services) is a web server in Windows that hosts and manages web applications, such as ASP.NET applications.

26.  What is the purpose of ASP.NET Core middleware?
 ASP.NET Core middleware is software components that can be used to handle HTTP requests and responses in an ASP.NET Core application, such as authentication, logging, or routing.

27.  What is the purpose of Dependency Injection in .NET?
 Dependency Injection is a design pattern in .NET that allows you to separate the creation and management of objects from their dependencies, making your code more modular, testable, and maintainable.

28.  What is the purpose of the SOLID principles in .NET?
 The SOLID principles are a set of guidelines in .NET that promote good object-oriented design, such as Single Responsibility Principle, Open-Closed Principle, Liskov Substitution Principle, Interface Segregation Principle, and Dependency Inversion Principle.

29.  What is the purpose of design patterns in .NET?
 Design patterns are reusable solutions to common software design problems in .NET, such as Factory, Singleton, Adapter, Decorator, or Observer.

30.  What is Garbage Collection in .NET?
 Garbage Collection is a process in .NET that automatically frees memory that is no longer used by the application, which helps to prevent memory leaks and improve performance.

31.  What is the purpose of AppDomain in .NET?
 AppDomain is a boundary in .NET that isolates a group of assemblies and provides a separate environment for their execution, which helps to improve security, reliability, and manageability.

32.  What is Reflection.Emit in .NET?
 Reflection.Emit is a feature in .NET that allows you to generate IL code at runtime and create dynamic types and methods, which can be useful for code generation, optimization, or dynamic programming.

33.  What is the purpose of Unit Testing in .NET?
 Unit Testing is a software testing approach that involves testing individual units or components of a software application in isolation to ensure that they function as intended. In .NET, unit testing is often used to ensure that code written in C#, VB.NET, or other .NET languages meets the expected behavior and Overall, the purpose of Unit Testing in .NET is to ensure that each individual unit of code is reliable, maintainable, and functions as intended, which helps to improve the quality and reliability of the application as a whole.

34.  What is Mocking in .NET?
 Mocking is a technique in .NET that involves creating fake objects (mocks) to simulate the behavior of real objects during testing, which helps to isolate the unit under test and improve test coverage.

35.  What is Code Review in .NET?
 Code Review is a practice in .NET that involves reviewing code written by other developers to identify defects, improve quality, and share knowledge, which helps to prevent bugs, increase collaboration, and maintain standards.

36.  What is Continuous Integration in .NET?
 Continuous Integration is a practice in .NET that involves building, testing, and deploying software changes automatically and frequently, which helps to improve quality, reduce risk, and increase feedback.

37.  What is Continuous Deployment in .NET?
 Continuous Deployment is a practice in .NET that involves automatically deploying software changes to production as soon as they pass a series of tests and quality checks, which helps to increase speed, reduce downtime, and improve customer satisfaction.

38.  What is the purpose of a Design Document in .NET?
 A Design Document is a document in .NET that describes the architecture, design, and implementation of a software system, which helps to communicate ideas, clarify requirements, and guide development.

39.  What is the purpose of a Technical Specification in .NET?
 A Technical Specification is a document in .NET that specifies the technical requirements, standards, and guidelines for a software system, which helps to ensure consistency, compatibility, and quality.

40.  What is the purpose of a Test Plan in .NET?
 A Test Plan is a document in .NET that describes the approach, scope, and criteria for testing a software system, which helps to ensure that the system meets the requirements, performs as expected, and is reliable.

41.  What is the purpose of a Code Review Checklist in .NET?
 A Code Review Checklist is a document in .NET that lists the common issues, best practices, and standards to review during a code review, which helps to ensure consistency, quality, and maintainability.

42.  What is the difference between Unit Testing and Integration Testing?
 Unit Testing is a type of testing in .NET that tests individual units of code in isolation, while Integration Testing is a type of testing in .NET that tests the interactions between different units of code or between different systems.

43.  What is the purpose of Load Testing in .NET?
 Load Testing is a type of testing in .NET that involves simulating high loads and traffic on a software system to measure its performance, scalability, and reliability under stress.

44.  What is the purpose of Security Testing in .NET?
 Security Testing is a type of testing in .NET that involves identifying and mitigating security risks and vulnerabilities in a software system, which helps to prevent data breaches, hacking, or unauthorized access.

45.  What is the purpose of Performance Testing in .NET?
 Performance Testing is a type of testing in .NET that involves measuring and optimizing the performance and speed of a software system, which helps to ensure that the system meets the performance requirements and user expectations.

46.  What is the difference between Debugging and Testing in .NET?
 Debugging is a process in .NET that involves identifying and fixing defects in a software system during development, while Testing is a process in .NET that involves verifying and validating the functionality, quality, and performance of a software system before and after deployment.

47.  What is the difference between Build and Release in .NET?
 Build is a process in .NET that involves compiling, linking, and packaging the source code into a deployable format, while Release is a process in .NET that involves deploying, configuring, and testing the software system in a production environment.

48.  What is the purpose of a Bug Report in .NET?
 A Bug Report is a document in .NET that describes a defect or issue found in a software system, which helps to track, prioritize, and resolve the problem.

49.  What is the difference between .NET Framework and .NET Core?
 .NET Framework is a proprietary software framework in .NET that supports Windows-based applications and runs only on the Windows operating system, while .NET Core is an open-source software framework in .NET that supports cross-platform applications and runs on Windows, Linux, and macOS. Additionally, .NET Core is designed to be lightweight, modular, and scalable compared to the more comprehensive .NET Framework.