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.Net Interview Questions

There are given top frequently asked .Net interview questions and answers that has been asked in many companies. Let's see the list of top Dot Net interview questions.

1) What is .NET?

.NET is a framework for software development. It is just like other software development framework like (J2EE). It provides runtime capabilities and a rich set of pre-built functionality in the form of class library and API's. This .NET framework is an environment to build, deploy and run web services and other applications.

The .NET framework contains three main parts:

  • Common Language Runtime
  • Framework classes
  • ASP.NET

2) How many languages are supported by .NET at present time?

When .NET was introduced first time, it supports many languages like VB.NET,C#,COBOL, and Perl etc. At present time it supports almost 44 languages.

3) How is it possible for .NET to support many languages?

The .NET language code is compiled to Microsoft Intermediate Language (MSIL). The generated code is called managed code. This managed code is run in .NET environment. So after compilation the language is not a barrier and the code can call or use function of another language also.

4) Is ASP.NET different from ASP? If yes, explain how?

Yes, ASP.NET is different from ASP. These are the main differences:

  • ASP.NET is developed by Microsoft to create dynamic web applications while ASP (Active Server Pages) is a Microsoft's server side technology use to create web pages.
  • ASP.NET is compiled while ASP is interpreted.
  • ASP uses the technology named ADO while ASP.NET uses ADO.NET.
  • ASP.NET is completely object oriented while ASP is partially object oriented.

5) What is the state management in ASP.NET?

State management is a technique that is used to manage a state of an object on different request. It is very important to manage state in any web application. There are two types of state management systems in ASP.NET.

  • Client side state management
  • Server side state management

6) What is the difference between trace and debug?

Debug class is used to debug builds while Trace is used for both debug and release builds.

7) How to retrieve user name in case of Window Authentication?

System.Environment.UserName

8) What is the difference between Hash table and Array list?

Hash table stores data in the form of value pair and name while Array list stores only values.

You need to pass name to access value from the Hash table while in Array, you need to pass index number to access value.

In Array, you can store only similar type of data type while in Hash table you can store different type of data types. ex. int, string etc.

9) What is HTTPhandler?

HttpHandler is a low level request and response API which is made to service incoming Http request. Every incoming Http request recieved by ASP.NET is ultimately processed by a instance of a class that implements HttpHandler.

10) What is .NET Framework and what are the main components of it?

.NET Framework facilitates the developer to develop, run and deploy the applications like console application, window Forms applications, web applications, web services, window services etc. It also provides environment to create sharable components to be used in distributed computing architecture.

Main components of .Net Framework:

  • Class library
  • Common Language Runtime (CLR)
  • Dynamic Language Runtime (DLR)
  • Application Domains
  • Runtime Hosts
  • Cross-language interoperability
  • Framework security
  • Profiling etc.

11) What is manifest in .NET Framework?

Manifest is used to store assembly metadata. It contains all the metadata which are necessary for following things.

  • Version of assembly
  • Security identity
  • Scope of the assembly
  • To resolve references to resources and classes

12) What are the memory-mapped files?

Memory-mapped files are used to map the content of a file to the logical address of an application. It makes you able to run multiple process on the same machine to share data with each other. To obtain a memory mapped file object, you can use the method MemoryMappedFile.CreateFromFiles( ). It represents a persistent memory-mapped file from a file on disk.

13) Which method is used to enforce garbage collection in .NET?

System.GC.Collect() method.

14) What is the difference between dispose() and finalize()?

Although Dispose and Finalize both methods are used by CLR to perform garbage collection of runtime objects of .NET applications but there is a difference between them.

The Finalize method is called automatically by the runtime while the Dispose method is called by the programmer.

15) Explain the Code Access Security (CAS) in .NET framework.

.NET security model is used to prevent unauthorized access of resources and operations and also restrict the codes to perform particular tasks. Code Access Security is a part of that .NET security.

16) What is Garbage collection?

Garbage collection is used to prevent memory leaks during execution of programs. There is a low-priority process name as garbage collector manages the allocation and deallocation a memory for applications. It also checks for the unreferenced variables and objects. If there is ny object which is no further used by application the Garbage collector frees up the memory from that object.

17) How can you identify that the page is post back?

There is a property, named as "IsPostBack" property. You can check it to know that the page is post backed or not.

18) What is variable and constant in .NET programming language?

Variable: A variable is a data storage location in the computer memory that contains a value and has a meaningful name. Every variable is attached to a data type which determines what type of value can be stored in the variable.

Variables can be declared by using the following syntax:

Constant: Constant is also similar to the variable except that the value. Value once assigned to a constant can't be changed. Constants must be initialized at the same time they are declared.

Constants can be declared by using the following syntax:

19) If you want to replace multiple if-else statements in code, which statement will you use?

In Visual basic, we can use Select-Case statement to replace multiple If-Else statement. In C#, we should use Switch-Case statement to replace multiple If-Else statement.