🚀 Top 30 C#, .NET Core, ASP. NET Core & EF Core Interview Questions Every .NET Developer Should Know
Whether you're preparing for your next interview or brushing up on your .NET fundamentals, these are some of the most frequently asked interview questions.

📌 1. C# & .NET Core:
What are the new features of C# you have used?
What is Dependency Injection (DI), and how does it work in .NET Core?
What is the difference between AddTransient, AddScoped, and AddSingleton?
What is Middleware? How do you create custom middleware?
What is asynchronous programming? Explain async and await.
What is the difference between Task, Thread, and async/await?
What is Garbage Collection (GC) in .NET?
What is IDisposable, and when should you use it?
What is IConfiguration?
What is the Options Pattern?

🌐 2. ASP.NET Core Web API:
Explain the complete request lifecycle in ASP. NET Core.
How do you secure a Web API?
How does JWT Authentication work?
What is the difference between Authentication and Authorization?
What are Filters in ASP. NET Core?
What is Model Validation?
What is API Versioning?
What is CORS, and why is it needed?
What are Action Filters and Exception Filters?
How do you implement Global Exception Handling?

🗄 3. Entity Framework Core:
What is Entity Framework Core?
What is the difference between Code First and Database First?
What are Migrations?
What is the difference between First(), FirstOrDefault(), Single(), and SingleOrDefault()?
What is the difference between Eager Loading, Lazy Loading, and Explicit Loading?
What is LINQ?
How do you improve Entity Framework Core performance?
What is AsNoTracking(), and when should you use it?
How do you handle Transactions in EF Core?
Explain the Repository Pattern and Unit of Work Pattern.

join Telegram:
https://t.me/coder_baba

💡 Interview Tip: Don't just memorize the definitions. Be prepared to explain each concept with practical examples and real-world scenarios from your projects.
Which of these questions do you find the most challenging? Share your thoughts in the comments! 👇
#DotNet #CSharp #ASPNetCore #WebAPI #EntityFrameworkCore #EFCore #SoftwareEngineering #BackendDevelopment #Programming #CodingInterview #InterviewPreparation #DotNetDeveloper #TechCareers

📘 Most Asked .NET Interview Questions (Covers 90% of .NET Interviews)

If you're preparing for a .NET Developer interview, the following questions cover most of the topics commonly asked in technical rounds.
Based on my recent interview experience, these are the questions that were asked repeatedly. If you're comfortable answering these, you'll be well-prepared for the majority of .NET interviews.

ASP .NET Core / ASP. NET MVC / ASP. NET Web API:

C# Fundamentals
What is the difference between ASP. NET and ASP. NET Core?
What are the latest features introduced in .NET 10 and the latest version of C#?
What are the four pillars of OOP? Explain each.
What is the difference between Abstraction and Encapsulation?
What is the difference between an Abstract Class and an Interface?
What is a Static Class, and when should you use it?
What is Polymorphism? Explain its types.
What is a Sealed Class?
What are Access Modifiers in C#? Explain their types.
What are Value Types and Reference Types?
What is the difference between a Struct and a Class?
What is the using keyword in C# and .NET?
What are readonly and static variables?
What is the difference between String and StringBuilder?
What are Extension Methods? Explain with an example.

ASP. NET Core:

What is Dependency Injection (DI), and why is it used?
What is Middleware?
What is Routing in ASP. NET Core?
What are Filters?
What is an Action Filter?
How do you implement Global Exception Handling?
What are async and await, and why are they used?
What is the difference between Task and Thread?
What is the difference between IEnumerable and IQueryable?
Explain JWT Authentication. Where is the JWT token typically stored?
Which Dependency Injection lifetime is commonly used for DbContext, and why?
Explain your project's architecture.
Which Design Patterns have you used in your project?
What is the Code First approach? Can you create a database schema without manually writing SQL?
What is the difference between the PUT and PATCH HTTP methods?
Why do we use POST and PUT instead of GET for data modification?
Explain the ASP.NET Core MVC request lifecycle.
What is LINQ? Explain commonly used methods and how to remove duplicate values.
Explain Eager Loading, Lazy Loading, and Explicit Loading.
What is the difference between ViewData, ViewBag, and TempData?
What are Sessions and Cookies?
What is the difference between SOAP API and REST API?
What is CORS, and why is it required?

Coding Questions:

Be prepared to write code for the following:
Print an infinite loop.
Reverse a string using a loop.
Check whether a string is a palindrome.
Exception handling (e.g., divide-by-zero scenario).
Find whether a number is prime.
Find duplicate elements in an array.
Reverse an array.
Find the second-largest number.
Count character occurrences in a string.
Fibonacci series.
Factorial of a number.
Armstrong number.
Remove duplicate characters from a string.

SQL Server:

How do you optimize a Stored Procedure?
How do you measure the execution time of a Stored Procedure?
What is the difference between Clustered and Non-Clustered Indexes?
How do you implement Transactions in a Stored Procedure?
What is the difference between a Function and a Stored Procedure?
What is the difference between a Stored Procedure and a View?
Write a query to find the 5th highest salary from an Employee table.
Write a query to find the Top 3 highest salaries from an Employee table.
What are SQL Constraints?
What is the difference between DELETE, DROP, and TRUNCATE?
Why can DELETE be rolled back, while TRUNCATE behaves differently in many scenarios?
What are CTEs (Common Table Expressions) and Temporary Tables? When would you use each?

💡 Interview Preparation Tips
Focus on understanding concepts instead of memorizing answers.
Practice coding questions on paper or in an online editor.
Be ready to explain your project's architecture, your responsibilities, and the technical decisions you made.
Prepare SQL queries without relying on IntelliSense.
Revise C#, ASP. NET Core, Entity Framework Core, SQL Server, Design Patterns, Dependency Injection, Authentication, and REST API concepts.
Mastering these topics will prepare you for approximately 90% of .NET Developer interviews, especially for professionals with 2–8 years of experience.
All the best for your next .NET interview! 🚀

Full Stack .NET Developer roles?

𝗖# / .𝗡𝗘𝗧 𝗖𝗼𝗿𝗲
• Explain the differences between IEnumerable, IQueryable, and IAsyncEnumerable
• How does async/await work under the hood? What's a deadlock scenario with .Result or .Wait()?
• Walk me through the .NET Core middleware pipeline
• Difference between Scoped, Transient, and Singleton in DI — give a real bug you've hit
• How would you implement a CancellationToken across a chain of async calls?

𝗘𝗙 𝗖𝗼𝗿𝗲
• Difference between Include vs explicit loading vs lazy loading — when would each bite you in production?
• How does EF Core track changes internally (change tracker, snapshot vs proxy)?
• N+1 query problem — how have you actually caught and fixed this?
• Migrations in a multi-developer team — how do you avoid conflicts?
• Dapper vs EF Core — when would you choose one over the other?

𝗦𝗤𝗟
• Explain clustered vs non-clustered indexes with an example of when an index made things worse
• Window functions — write a query using ROW_NUMBER() or RANK() to solve a real problem
• How do you detect and resolve a deadlock in SQL Server?
• Normalization vs denormalization — when did you deliberately break 3NF?
• Difference between stored procedures and ORMs from a performance/security lens

𝗔𝗻𝗴𝘂𝗹𝗮𝗿
• Explain change detection (default vs OnPush) — how would you optimize a slow-rendering list?
• RxJS: difference between switchMap, mergeMap, concatMap, exhaustMap — give a use case for each
• How do you handle unsubscribing from observables at scale?
• Difference between Reactive Forms and Template-driven Forms — why would a BFSI app prefer one?
• How does Angular's dependency injection hierarchy work across modules?

𝗔𝘇𝘂𝗿𝗲
• Azure App Service vs Azure Functions vs AKS — how do you decide?
• How would you design a secure, scalable multi-tenant architecture on Azure?
• Explain Azure Service Bus vs Event Grid vs Event Hub — when does each fit?
• How do you handle secrets and connection strings in production (Key Vault, Managed Identity)?
• Walk me through your CI/CD pipeline in Azure DevOps

𝗢𝗢𝗣𝘀
• Explain SOLID with one real violation you've refactored
• Composition vs inheritance — when have you chosen one deliberately?
• How would you design a class hierarchy for a payment gateway integration supporting multiple providers?
• Difference between abstraction and encapsulation with a non-textbook example

𝗪𝗲𝗯 𝗔𝗽𝗽 𝗢𝗽𝘁𝗶𝗺𝗶𝘇𝗮𝘁𝗶𝗼𝗻
• How would you diagnose a slow API endpoint in production — walk through your process
• Caching strategies: where does Redis fit vs in-memory vs CDN caching?
• How do you reduce payload size and improve API response times for high-traffic endpoints?
• Explain how you'd design rate limiting for a public-facing API
• Lazy loading, bundle splitting, and tree shaking — how have you applied these in Angular?