.NET is a widely used software framework for developing mobile, web and Windows-based applications. Understanding common .NET interview questions can be helpful if you are applying for a .NET developer or a similar position. In addition to the technical aspects of the .NET framework, interviewers may also test your knowledge of coding and development practices. In this article, we list some of the common .NET interview questions, along with tips and sample answers.
Basic .NET interview questions and answers for freshers
Here are some common .NET interview questions and sample answers for beginners:
1. What is the .NET framework?
Tell the interviewer about the .NET framework and its features and applications. Focus on the practical aspects to show your ability to use the system effectively.
Example: “.NET is a software framework originally developed for Windows-based applications by Microsoft Corporation. We can also use it for developing web and mobile-based applications. It is a complete system of libraries, classes and APIs (application programming interface) that supports the building and deployment of applications. It offers the flexibility to write codes across several programming languages.”
2. What programming languages does the .NET framework support?
List some of the popular programming languages the framework supports. Additionally, you can also tell the interviewer about your programming knowledge and experience in those languages.
Example: “The .NET framework supports a large number of programming languages, including Microsoft and non-Microsoft languages. Some of the popular programming languages it supports include C#, C++, VB, Perl, Cobol, F# and JScript. My B.Tech project involved developing a shopping cart using the C#.net language. I am also familiar with Cobol, C++ and VB since I had joined a private institute to learn them alongside my graduation.”
3. Name some of the important components of the .NET framework.
The .NET framework comprises several components. Make sure you include the essential ones in your answer, such as the class library and CLR (common language runtime). Consider explaining the logic behind why they are the most essential components. It will show the interviewer that you can apply critical thinking to deal with a difficult situation.
Example: “The .NET framework comprises several components, such as CLR (common language runtime), application domain, common type system, profiling and class library. I believe CLR and class library are the most important components of these. The CLR sets the foundation by providing tools and resources for developing an application. The class library provides the essential classes of common functionalities shareable across different applications.”
4. What is CTS in the .NET framework?
Define CTS and explain its concept. Also, discuss its utility and functions in programming so that the interviewer knows that you have a clear understanding of its technical aspects.
Example: “CTS or the Common Type System is a set of rules and standards for representing type definitions and their values in computer memory. In computer programming, a type defines a set of values (e.g., integers from 0 to 10) and the operations you can perform on those values (e.g., addition and subtraction). CTS facilitates sharing of information between computer programs written in different languages. It establishes the rules for type visibility and inheritance.”
5. What is CLR?
Begin with the full form of CLR and explain its usage and importance. Talk about the functions it handles, such as security checks and memory management.
Example: “CLR refers to common language runtime. It is an essential component of the .NET framework that aids application development and provides a secure environment for an application's execution. When we compile a code in any programming language, the .NET framework converts the code into an intermediate language. The CLR then performs various operations on the code, such as security check, memory management and loading assemblies. The code that CLR runs is called managed code.”
6. What is CLS?
Define what CLS stands for. Discuss how it enables seamless integration of programming languages.
Example: “CLS or Common Language Specification is a subset of CTS. It is a set of rules for programming languages that must be followed in the .NET framework. It helps turn a program into a CIL (Common Intermediate Language) code so that we can write different parts of a program in different languages. Thus, CLS enables seamless communication between different .NET compatible languages.”
7. What is the use of JIT in the .NET framework?
Explain how the JIT compiler helps in program execution. Talk about the cross-platform support it provides.
Example: “JIT is a ‘just in time' compiler. For executing a program, first, we need to convert the source code into an intermediate language. A language-specific compiler takes care of this. We then need to convert the intermediate language into the machine code. A JIT compiler helps us with this task. A JIT compiler is so-called because it converts an intermediate language into machine code as and when required instead of converting the entire code at once.”
Read more: How to Succeed in Your First Interview
Advanced .NET interview questions and answers for experienced professionals
Following are some of the advanced-level .NET interview questions and sample answers for experienced professionals:
1. What is a managed code? How does it differ from an unmanaged code?
This question tests your knowledge about the code execution process in the .NET framework. You can talk about the role of CLR in executing the managed code and how unmanaged code is independent of the managed runtime environment.
Example: “A managed code is one which runs in a managed runtime environment. For example, a code executed by the CLR in the .NET framework is a managed code. A managed runtime environment automatically manages and executes a code by providing various services like garbage collection, exception handling and memory allocation. On the other hand, an unmanaged code runs in an independent environment. An operating system directly executes it without the interference of the CLR or JIT.”
2. Explain the garbage collection process.
Garbage collection is one of the essential functions of the CLR. You can discuss how it helps in memory optimisation and increasing the efficiency of developers.
Example: “The CLR has the garbage collector, which automatically allocates and releases memory for an application. When the CLR initialises the garbage collector, it allocates memory for the objects. This memory segment is known as managed heap. The managed heap is organised into three generations, namely 0, 1 and 2. Generation 0 is meant for short-lived objects. The garbage collector releases the code objects in this heap more often than in Generations 1 and 2.
The garbage collector first identifies the live objects. Then, it updates the references for compacting those objects. Finally, it releases the space used by the dead code objects and transports the remaining code to an older segment.”
3. Explain the difference between Response.Redirect and Server.Transfer methods?
Although both of these methods have the same function of transferring a user to another web page, there is a difference in the way they achieve this objective. Explain the process involved in each case so that the interviewer knows that you have a clear idea of the technical aspects of these methods.
Example: “Both these methods are meant for taking users from one web page to another. Response.Redirect takes a user to another web page by redirecting the browser. Thus, the web address of the new page will be registered in the user's browser history. On the other hand, the Server.Transfer method kills the current web page and opens the new page afresh. It does not make any round trip back to the user's browser.”
4. Describe the EXE and DLL modules.
Both of these are assembly executable modules. Define each term and briefly explain the important features.
Example: “EXE is an executable file. It runs the application. The system automatically generates an EXE file when we build an application. We cannot share an EXE file with other applications. DLL stands for dynamic link library. We use it for storing hidden codes. An application can have multiple DLLs. We can also share DLLs with other applications.”
5. Explain the passport authentication process.
The passport authentication process uses Microsoft's passport service to authenticate users. Describe the authentication process in simple terms.
Example: “In the passport authentication process, an application first looks for the encrypted authentication cookie. If the user is already signed into the passport, the application considers them as authenticated. If the application does not find the passport cookie, it redirects the user to the passport login page. When the user logs in, the passport service authenticates the details, stores the authentication credentials on the user's machine and redirects them to the requested web page.”
6. What is cross-page posting?
Cross-page posting is a useful property in ASP.NET that enables posting data from one page to another. You can include the features and benefits of this property in your response.
Example: “By default, when we click on a button, it reloads the same page. For example, when we click on the submit button, it stores the data on the same page that hosts the button. However, if we want to store the data on a different page, we need to use cross-page posting in our project. Cross-page posting refers to posting form data to another page without reloading the current page. We can achieve cross-page posting by using the POSTBACKURL property.”