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.NET Developer interview questions & mock practice

A .NET Developer interview in 2026 runs across 4 rounds — c# / oop fundamentals, asp.net core round, database & sql server, system design / project deep-dive. Below are the most-asked .NET Developer interview questions and a focused prep plan. Rehearse every answer with OnJob's free AI mock interview and get instant, specific feedback before the real one.

C#ASP.NET CoreEntity FrameworkSQL ServerLINQWeb APIOOPAzure

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Practise your .NET Developer interview now — free

Step through the 13 most-asked .NET Developer questions one at a time, under a timer, just like the real thing. Jot your answer, then reveal what a strong answer covers. No signup needed to practise.

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Interview rounds

The .NET Developer interview process

C#, ASP.NET Core and SQL Server — the enterprise backend interview favoured by GCCs, banking, insurance and Microsoft-stack services firms across India.

1

C# / OOP fundamentals

Language features, OOP principles, value vs reference types, collections and LINQ.

2

ASP.NET Core round

Web API design, middleware pipeline, dependency injection and Entity Framework.

3

Database & SQL Server

Schema design, stored procedures, indexing and query tuning.

4

System design / project deep-dive

Designing a scalable service and discussing your past .NET projects.

Most-asked questions

Most-asked .NET Developer interview questions

13 of the questions .NET Developer candidates are asked most often in India. Practise answering each one out loud in your AI mock interview.

1. What is the difference between value types and reference types in C#?
2. Explain the difference between an abstract class and an interface in C#.
3. What is the difference between IEnumerable, ICollection and IList?
4. What are async and await, and how do they work in C#?
5. Explain the difference between .NET Framework, .NET Core and .NET 5+.
6. What is dependency injection and how does ASP.NET Core support it out of the box?
7. Explain the request middleware pipeline in ASP.NET Core.
8. What is the difference between String and StringBuilder?
9. What are delegates, and how do Func, Action and Predicate differ?
10. Explain deferred vs immediate execution in LINQ.
11. What is the difference between ref and out parameters?
12. How does Entity Framework track changes, and what is lazy vs eager loading?
13. What is the difference between Task and Thread in C#?

How to prepare

How to prepare for your .NET Developer interview

Master C# fundamentals: OOP, generics, delegates and events, LINQ, and value vs reference type semantics.

Understand async/await deeply: the Task model, ConfigureAwait, deadlocks and how the thread pool is used.

Be fluent in ASP.NET Core: middleware order, built-in DI lifetimes (transient/scoped/singleton) and Web API conventions.

Know Entity Framework Core and SQL Server: migrations, change tracking, lazy vs eager loading and writing tuned queries.

Revise design patterns commonly probed on the .NET stack: repository, factory, singleton and SOLID principles.

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Interview prep guides

.NET Developer interview — FAQs

What questions are asked in a .NET Developer interview?

Common .NET Developer interview questions include: What is the difference between value types and reference types in C#? Explain the difference between an abstract class and an interface in C#. What is the difference between IEnumerable, ICollection and IList? What are async and await, and how do they work in C#? Interviews usually run across 4 rounds — C# / OOP fundamentals, ASP.NET Core round, Database & SQL Server, System design / project deep-dive. Practice all of them with instant AI feedback using OnJob's free mock interview.

How many rounds are in a .NET Developer interview?

A typical .NET Developer interview has 4 rounds: C# / OOP fundamentals (Language features, OOP principles, value vs reference types, collections and LINQ.); ASP.NET Core round (Web API design, middleware pipeline, dependency injection and Entity Framework.); Database & SQL Server (Schema design, stored procedures, indexing and query tuning.); System design / project deep-dive (Designing a scalable service and discussing your past .NET projects.).

How do I prepare for a .NET Developer interview?

To prepare for a .NET Developer interview: Master C# fundamentals: OOP, generics, delegates and events, LINQ, and value vs reference type semantics. Understand async/await deeply: the Task model, ConfigureAwait, deadlocks and how the thread pool is used. Be fluent in ASP.NET Core: middleware order, built-in DI lifetimes (transient/scoped/singleton) and Web API conventions. Then run a full AI mock interview on OnJob to rehearse out loud and get instant, specific feedback before the real thing.

What skills do I need for a .NET Developer role?

Core .NET Developer skills tested in interviews include C#, ASP.NET Core, Entity Framework, SQL Server, LINQ, Web API, OOP, Azure. OnJob shows you exactly which of these skills stand between you and a 100% match on every live .NET Developer job.

Is OnJob's .NET Developer mock interview free?

Yes. OnJob's AI mock interview is free to start (₹0) and gives you instant feedback on your answers. Pro (₹99/month) adds unlimited interview-prep AI alongside recruiter tracking and unlimited applications.

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Rehearse every .NET Developer question out loud with OnJob's AI mock interview and get instant, specific feedback. Then apply to AI-matched jobs in one click — free to start.

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