.NET Interview Questions

1. What is the .NET Framework?

Answer: The .NET Framework is a software development framework from Microsoft. It provides a controlled programming environment where software can be developed, installed, and executed on Windows-based operating systems. It includes a large class library named Framework Class Library (FCL) and provides language interoperability across several programming languages.

2. Explain Common Language Runtime (CLR) in .NET.

Answer: CLR is the runtime environment in the .NET Framework that runs the codes and helps in making the development process easier by providing services such as memory management, security management, and exception handling. It also allows for interoperability between different .NET languages.

3. What is Managed Code?

Answer: Managed code is code executed by the CLR. It benefits from features such as cross-language integration, cross-platform support, security, memory management, and exception handling, which are automatically handled by the CLR.

4. What are the main components of .NET?

Answer: The main components of .NET include the Common Language Runtime (CLR), the .NET Framework Class Library, ASP.NET, Windows Forms, Windows Presentation Foundation (WPF), Windows Communication Foundation (WCF), and Language Integrated Query (LINQ).

5. Explain the concept of Garbage Collection in .NET.

Answer: Garbage Collection (GC) in .NET is a process through which the system automatically reclaims memory by identifying and disposing of objects that are no longer in use by the application, thus preventing memory leaks and improving application performance.

6. What is C#?

Answer: C# is a type-safe, managed, object-oriented programming language developed by Microsoft. It is designed for building a variety of applications that run on the .NET Framework, including desktop applications, web services, and web applications.

7. What is the difference between Value Type and Reference Type in C#?

Answer: Value types store data directly in their memory space, whereas reference types store a reference to the memory location where the actual data is held. Value types are stored in the stack, while reference types are stored in the heap.

8. Explain the concept of Exception Handling in .NET.

Answer: Exception handling in .NET is a mechanism to handle runtime errors. It uses try, catch, and finally blocks to gracefully handle exceptions and take necessary action without crashing the program.

9. What is ASP.NET?

Answer: ASP.NET is an open-source server-side web application framework designed for web development to produce dynamic web pages. It was developed by Microsoft to allow programmers to build dynamic websites, web applications, and web services.

10. Describe the MVC architecture.

Answer: MVC stands for Model-View-Controller. It's an architectural pattern used for developing user interfaces. It divides an application into three interconnected parts (Model, View, and Controller) to separate internal representations of information from the ways information is presented to and accepted from the user.

11. What is Entity Framework?

Answer: Entity Framework is an open-source object-relational mapping (ORM) framework for ADO.NET, part of the .NET Framework. It enables developers to work with data in the form of domain-specific objects and properties, without having to concern themselves with the underlying database tables and columns where this data is stored.

12. Explain LINQ.

Answer: LINQ (Language Integrated Query) is a Microsoft .NET Framework component that adds native data querying capabilities to .NET languages, using a syntax reminiscent of SQL but integrated with C# or VB.NET.

13. What is a Delegate in C#?

Answer: A delegate in C# is a type that represents references to methods with a particular parameter list and return type. Delegates are used to pass methods as arguments to other methods and can be used to define callback methods.

14. What is the difference between a Class and an Object in C#?

Answer: A class in C# is a blueprint for creating objects. An object is an instance of a class, containing actual data and functionalities as defined in the class.

15. Explain the concept of Polymorphism in C#.

Answer: Polymorphism is a concept in C# that allows methods to do different things based on the object that it is acting upon. It includes compile-time (method overloading, operator overloading) and runtime polymorphism (method overriding).

16. What is the use of the `using` statement in C#?

Answer: The `using` statement in C# is used to ensure that IDisposable objects, such

as files and database connections, are disposed of properly. It provides a syntactic shortcut for calling the Dispose method on objects, regardless of how the block is exited.

17. Describe the role of Interfaces in C#.

Answer: Interfaces in C# define a contract for classes and structs. An interface can contain declarations for methods, properties, events, and indexers. A class or struct that implements an interface must provide implementations for the members defined by the interface.

18. What is WPF?

Answer: WPF (Windows Presentation Foundation) is a graphical subsystem by Microsoft for rendering user interfaces in Windows-based applications. WPF uses XAML (an XML-based language) for designing UI elements and supports 2D/3D graphics, animation, styles, templates, and more.

19. Explain the role of WCF.

Answer: WCF (Windows Communication Foundation) is a framework for building service-oriented applications. It enables developers to build secure, reliable, transacted solutions that integrate across platforms and interoperate with existing investments.

20. What is Dependency Injection in .NET?

Answer: Dependency Injection (DI) is a design pattern used to implement IoC (Inversion of Control), allowing for more modular and testable software. In .NET, DI enables you to inject objects into a class, rather than creating them inside the class, thus promoting loose coupling.

21. Describe Async/Await in C#.

Answer: Async and Await are keywords in C# that are used to make asynchronous programming simpler. The async keyword is used to specify that a method is asynchronous, and the await keyword is used to pause the execution of the method until an awaited asynchronous operation is completed.

22. What is a Lambda Expression in C#?

Answer: A lambda expression in C# is a concise way to represent an anonymous method. It can contain expressions and statements, and can be used to create delegates or expression tree types.

23. Explain the Singleton Pattern.

Answer: The Singleton Pattern is a design pattern that ensures a class has only one instance and provides a global point of access to it. It's used in scenarios where exactly one object is needed to coordinate actions across the system.

24. What are Attributes in C#?

Answer: Attributes in C# are declarative tags used to convey information about the behaviors of various elements like classes, methods, structures, enumerators, assemblies, etc., at runtime.

25. How does .NET handle memory management?

Answer: .NET handles memory management through the use of the CLR, which includes a garbage collector (GC) that automatically manages the allocation and release of memory for your applications.

26. What is Code Access Security (CAS) in .NET?

Answer: Code Access Security (CAS) is a part of the .NET security model that prevents unauthorized access to resources and operations, and restricts the operations that code can perform, based on the identity of the code and the trust level granted to it.

27. What is the Global Assembly Cache (GAC)?

Answer: The Global Assembly Cache (GAC) is a machine-wide cache used to store assemblies that are intended to be shared by several applications on the computer.

28. Describe the process of creating a custom attribute in C#.

Answer: Creating a custom attribute in C# involves defining an attribute class by inheriting from the System.Attribute class, and using the AttributeUsage attribute to specify where the custom attribute can be applied. Custom attributes can then be retrieved at runtime using reflection.

29. What is ADO.NET?

Answer: ADO.NET is a data access technology from the Microsoft .NET Framework that provides communication between relational and non-relational systems through a common set of components.

30. How do you manage state in ASP.NET applications?

Answer: State management in ASP.NET can be managed using various methods like view state, session state, application state, cookies, and database storage, depending on the scope and lifetime of the data being stored.

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