Top 50 .NET Interview Questions 2026 — C#, ASP.NET Core, EF Core, Design Patterns
💼 These 50 .NET interview questions are asked in EVERY company —
from service companies to product startups to FAANG India.
Fresher to Senior level. With simple, clear answers and real code examples.
Watch this before every .NET interview. Bookmark it. Share it.
⏱️ TIMESTAMPS
0:00 - C# Fundamentals Q1-Q10 (Value types, ref/out, abstract vs interface)
4:00 - C# Advanced Q11-Q20 (async/await, LINQ, delegates, IQueryable)
8:00 - ASP.NET Core Q21-Q28 (Middleware, DI lifetimes, Minimal APIs, JWT)
12:00 - Entity Framework Core Q29-Q35 (Lazy loading, AsNoTracking, migrations)
16:00 - Design Patterns Q36-Q40 (Repository, CQRS, Singleton, Factory)
20:00 - Security & Auth Q41-Q45 (JWT, OAuth 2.0, CORS, SQL Injection)
23:00 - Performance Q46-Q50 (Caching, N+1 problem, connection pooling)
27:00 - System Design Questions (URL shortener, notification system, scaling)
30:00 - Tricky Questions Interviewers Love (deadlock, boxing, throw vs throw ex)
33:00 - Behavioral Questions (STAR method with real .NET examples)
🔥 QUESTIONS COVERED
✅ C# Fundamentals — value type vs reference type, sealed, partial classes
✅ async/await internals — why it doesn't create new threads
✅ DI lifetimes — Singleton vs Scoped vs Transient (captive dependency trap)
✅ IEnumerable vs IQueryable — the most common interview mistake
✅ EF Core — Eager vs Lazy vs Explicit loading, global query filters
✅ JWT authentication — full end-to-end flow explained
✅ Repository Pattern + CQRS — with real code examples
✅ N+1 query problem — what it is and how to fix it
✅ System design — design a URL shortener with .NET + Redis
✅ Tricky .NET — what happens when you call .Result on async (DEADLOCK!)
📚 TOPICS COVERED
C# 8-12 Features → Records, Pattern Matching, Primary Constructors
ASP.NET Core 8 → Middleware, Minimal APIs, Filters, Output Caching
Entity Framework → Code First, Migrations, Concurrency, Shadow Properties
Security → JWT, OAuth 2.0, CORS, SQL Injection prevention
Design Patterns → Repository, CQRS, Singleton, Factory, Circuit Breaker
Performance → Caching, AsNoTracking, Compiled Queries, Pagination
System Design → Scalability, Microservices, Event-driven patterns
Behavioral → STAR method with real project examples
🎯 WHO IS THIS FOR?
• .NET developers preparing for interviews in the next 7 days
• Freshers applying for their first ASP.NET Core job
• Mid-level developers targeting ₹20-40 LPA roles
• Senior developers aiming for ₹40-60 LPA positions
• Anyone switching from Java/Python to .NET
💡 HOW TO USE THIS VIDEO
1. Watch fully once — understand all concepts
2. Write code for each answer (don't just memorize)
3. Re-watch the sections you got wrong
4. Practice explaining answers out loud
5. Watch again the night before your interview
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💬 Comment: Which question caught you off guard?
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