What are the top .NET interview questions?

Top 10 .NET Interview Questions

Start your developer journey by acing your .NET interview. Here are the top .NET interview questions and answers to help you prepare. 

You’ve submitted your resume and portfolio. And, your interview schedule is coming up. It’s time to brush up on your .NET development knowledge. No matter your level of experience as a .NET developer, you will need to prepare for your technical interview.

.NET development is such a vast subject to prepare for. That is why you have to refresh your knowledge in areas you haven’t worked on for a long time. Additionally, it would be best to refamiliarize yourself with .NET tools, architecture, C#, SQL Servers, and more.

To help you prepare, we’ll discuss what you should expect in your interview. Furthermore, we’ve also collated the top .NET interview questions and tips on some sample answers.

What to Expect with the Interviewing Process

Technical interviews for frontend, backend or .NET developers are unlike any other. Interviewers are more interested in checking if you have the skills required for the position. Hence, .NET developers’ technical interviews are more like exams than question and answer.

So, what happens during the interviews? Here’s what each stage looks like:

1st Stage: Phone Screening

After seeing your resume and portfolio, the company’s human resource personnel will call you. During this call, they check if you have the qualifications for the open position. They will also see if you are enthusiastic about working with the company.

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2nd Stage: Remote Coding Challenge

After the phone screening, most companies will schedule you for a remote interview. They will give you a preliminary coding test and/or coding assignment. Depending on the company, they may do this over the phone, via Zoom or Skype, or their site.

3rd Stage: Onsite Interview and Coding Challenge

It will be during this stage where you have an in-person interview and coding challenges. Some companies will have you do the “whiteboard” test where you do a coding challenge on a whiteboard in front of a panel.

You will then explain your coding process to them. Further, the questions during this stage will be about .NET development and real-world instances.

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Top .NET Interview Questions

Knowing what to expect in each interview stage, we can now talk about the interview questions that commonly come up. Below are the top .NET interview questions and how to answer them.

1. Explain .NET framework.

This is a fundamental question for .NET job interviews. For interviewers, they usually ask this question to junior developers to gauge their in-depth knowledge. Hence, make your answer clear and concise.

Sample answer: “.NET is an open-source and cross-platform framework developed by Microsoft. As a developer, I use the framework to build different kinds of applications. What makes .NET very convenient is that you can use different programming languages, libraries, and editors to build web and mobile applications.”

2. How does .NET work?

Interviewers would want to dig deeper into your understanding of .NET development. They will want a clear and organized answer to this question. Also, try to use .NET technical terms in your response.

Sample answer: “.NET’s main components are the extensive class library, Framework Class Library (FCL), and Common Language Runtime (CLR). FCL enables several programming languages to use codes written using other languages. On the other hand, CLR is the software environment where we execute .NET applications.

As such, .NET applications use programming languages C# and F#. The Common Intermediate Language (CIL) compiles these languages. So, when you run .NET, CLR will take your file and convert CIL into code with Just In Time (JIT). Lastly, developers call the code written in .NET as managed code.”

3. Explain JIT.

Interviewers will ask this question as a follow-up to the previous one. You need to explain JIT clearly as the interviewers may want to check if you understand your last answer.

Sample answer: Simply put, JIT stands for “Just In Time.” It is a compiler used to convert intermediate code into the native language during execution.”

4. What is inheritance? Why is it important?

.NET developers should have in-depth knowledge about object-oriented programming. Consequently, you should explain what inheritance is and its importance.

Sample answer: “Inheritance allows developers to create new classes by reusing, modifying, and extending the defined behavior from other classes. Furthermore, developers can write and debug classes once and use the said classes to create new ones. Hence, the development process is sped up by reusing codes.

A class with inherited members is the base class, while those who inherit are the derived classes. In .NET, all classes are inheritable.”

5. Differentiate a class from an object.

Objects and classes are two of the most important elements in .NET development. So, .NET developers of all levels should be able to differentiate the two.

Sample answer: “A class is a template of the object. It describes the methods, behavior, states, and properties which the implementing object will have. Moreover, a class will only become an object once it is initiated. Hence, a class can have many instances of objects. And each of these objects has different properties.

So, in short, a class defines an object while an object is an instance of a class.”

6. What is ASP.NET?

For many starting developers, the difference between ASP.NET and .NET can be very confusing. So, make sure to differentiate them both through your answer.

Sample answer: “ASP.NET is a part of the .NET framework. It is an open-source server-side technology used to develop dynamic and powerful web pages. In addition, ASP.NET allows developers to access .NET’s classes and features. Therefore, it simplifies the development, testing, debugging, and deployment of web applications.”

7. Differentiate the Stack against the Heap.

Interviewers ask this question to see how deep your understanding of the .NET framework is. Your answer should also show that you have experience in using both the Stack and the Heap.

Sample answer: “First off, the Stack stores value types inherited from System.ValueType while reference types inherited from System.Object are in the Heap.

In short, the Stack is responsible for tracking what is executing and where each executing thread is. On the other hand, the Heap keeps track of the more specific objects or data.”

8. Explain the garbage collecting process in .NET.

Developers need to manage the memory allocation during application development. Hence, the garbage collection in .NET is one of its most vital features. Having an idea about the garbage collecting process will show the interviewers that you are a very experienced developer.

Sample answer: “Codes that are no longer in use are released through the garbage collecting is the process. There are three stages or generations in the process— Generation 0, 1, and 2. Generation 0 is more frequent, while both 1 and 2 happen very seldom.

The process starts with the garbage collector identifying live objects. Next, it updates the references for all the objects it will compact. Then, it will reclaim all the spaces that dead codes once occupied. Finally, the collector moves the remaining codes to an older segment.”

9. What is Caching?

In terms of application performance, speed is essential. And one way to increase the speed of your application is through Caching. Hence, .NET developers must know what it is.

Sample answer: “Caching is all about storing data in the memory temporarily. By doing so, your application can quickly access the data in the cache instead of looking for it in its original location. As a result, your application can open or load faster.

The three types of Caching are Page Caching, Fragment Caching, and Data Caching. In .NET, System.Runtime.Caching is the namespace used for Caching Information.”

10. How do you execute managed code?

For all developers, executing code is an essential function. However, executing managed code is specific to the .NET framework. The best answer to this question is to explain how to run managed code in the framework’s CLR environment.

Sample answer: “My process would be to write the code first. Next, I would compile the codes with a compiler. Using the compiler, I will turn the managed code into an intermediate language. Once done, .NET’s CLR will convert the intermediate language into native code. Finally, the framework will execute the resulting native code.”

Standout During Your .NET Interview

The best way to become a memorable candidate is to keep your answer to .NET interview questions simple and clear. Speak audibly and clearly. Make sure you are confident when answering the questions. 

Another way to stand out during your interview is to tailor your answers to the company’s needs. Make sure to ask clarifying questions. This way, you can make a response that the interviewers would want to hear. Always remember that the interviewers are looking for the following during your interview:

  • Your coding skills
  • Analytical skills
  • Communication skills
  • Problem-solving skills
  • Creativity
  • Handling feedback, both positive and negative
  • Can you fit with the company’s culture
  • Camaraderie

It would also help that you dress appropriately for your interview. Be courteous towards your interviewers. 

Lastly, always practice and prepare for your interviews. Make sure to do regular coding exercises and challenges. Join and enroll in .NET forums to learn about the framework’s latest developments. In addition, try to do mock interviews. This will help you improve your talking skills.

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