The .NET framework is used to build, run, and deploy applications on Windows and the web. And if you’re pursuing a role that uses it — like a Software Developer, Front-end Developer, or .NET Developer — you’ll be asked a series of .NET questions during your technical interview.
One of the best ways to prepare for .NET interview questions is to practice answering them in a mock interview. You can ask someone to play the role of the interviewer and ask you questions so you can practice answering them out loud in front of another person. If you’re interviewing over Zoom, you can do your mock interview on Zoom too, which can help you practice for a virtual interview. You can also practice on your own and record yourself, and then review the recording to find areas that you can improve.
To help you prepare for your upcoming interview, here are 12 .NET interview questions and tips on how to answer them.
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1. What is .NET?
Even technical interviews will kick off with an ice-breaker question or two, and this is a good example of one. The answer to this question is short and sweet, so you may want to throw in an interesting detail, like how long you’ve been using the .NET framework, that could lead to a conversation about your past experience and expertise.
To answer this question, you can discuss how .NET is a framework that people use to develop, run, and deploy software. The .NET framework has three primary components, including Common Language Runtime, ASP.NET, and Framework classes.
2. How many languages does .NET support?
This question is designed to see if you know and understand the flexibility that .NET makes available for programmers and the companies that employ them. You’ll want to mention that .NET supports over 60 languages, and if it fits in your answer, don’t hesitate to mention how this has benefited you and/or a past employer.
3. How can .NET support so many languages?
.NET uses Microsoft Intermediate Language (MSIL). The code this produces is referred to as managed code, and that’s what you run within a .NET ecosystem. The compilation process removes the barrier that would otherwise exist had the code not been re-made into MSIL.
4. How is ASP.NET different from ASP?
ASP.NET was created by Microsoft to enable dynamic web apps, but ASP is a server-side technology used to make web pages.
Also, ASP.NET produces compiled code, while ASP produces interpreted code. Another difference is that ASP.NET is fully object-oriented, but ASP is only partially object-oriented.
5. How are Trace and Debug different?
Debug and Trace are tools used in software development. Debug is a tool for debugging software that you build, and Trace is a tool that can be used with both debug and release builds.
Since Trace offers both features, some people gravitate toward it to debug their solutions instead of using two separate tools to complete the same task.
6. How are System.Text.StringBuilder and System.String different?
The main difference is that System.Text.StringBuilder can be changed while System.String is immutable. Even in languages, such as VB, where a System.String can be changed, internally any changes result in a new copy of the System.String. This isn’t the case with System.Text.StringBuilder, which makes it more performant.
System.Text.StringBuilder also incorporates a number of string manipulation methods that aren’t available with System.String.
7. How are namespace and assembly different from each other?
A namespace is used to group classes, while an assembly physically groups logical units. Plus, you can use a namespace across more than one assembly.
8. How do int and int32 differ from each other?
This is somewhat of a trick question because there isn’t a real difference between int and int32. When you answer this question, you can mention that int is merely an alias for int32.
9. How are session objects and application objects different?
A session object is used for maintaining a user’s session, while an application object maintains use for an entire application. In other words, after a session ends, a session object would no longer be useful — a new one would have to be created when the next session begins. With an application object, the object carries through from one session to the next within the same application.
10. How are hash tables and array lists different?
A hash table keeps data as a value pair and name, but an array list only stores values. You’re also required to pass a name if you want to access a value within a hash table. For an array list, you need to pass an index number to access a value. In addition, you can store different kinds of data types in a hash table, but in an array, only similar data types can be stored.
11. What are the benefits of using session?
The benefits of using session include the following:
- Session is secure because the session object is stored on the server, making it harder for a malicious actor to access it.
- Implementing and storing objects is straightforward in session.
- Session can store user data individually and separately from that of others.
- Session can store user data and states in various places around the application.
12. What are the drawbacks of using session?
Because session data gets stored in the server’s memory, you can experience excessive-performance overhead if you have a lot of users. There’s also the danger of overhead when you’re serializing and de-serializing your session data.
If you want to give an example when answering this question, you can illustrate the challenge of limited server memory by outlining the impact of X number of users, each performing actions that require an average of Y amount of memory. Then describe how this could cause a problem given the server’s available memory. If you’ve encountered a situation like this on a past project, be sure to discuss that and how you managed the issue. This can show your prospective employer that you have experience handling these types of real-world problems.
Looking for more interview help?
If you’re looking for more ways to prep for your interview, check out our complete guide to the technical interview, advice for answering behavioral questions, and tips for acing the whiteboard interview.
Our Career Center provides even more interview support, as well as job-hunting resources, like resume help and portfolio tips.
If you need a refresher on any of the topics covered in these questions, check out our Build Web Apps with ASP.NET skill path to learn how to build a variety of different kinds of apps or our Learn ASP.NET course that teaches the basics of designing effective, secure web apps using ASP.NET.
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