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Reference: Qwen3-32B model

1. C# Fundamentals ​

Focus on core language features and OOP principles, which are commonly tested in interviews.

Key Topics to Master: ​

  • Object-Oriented Programming (OOP):   - Classes, objects, inheritance, polymorphism, encapsulation, and abstraction.   - Example: Explain the difference between abstract classes and interfaces.

  • Generics and Collections:   - List<T>, Dictionary<TKey, TValue>, IEnumerable<T>, and IEnumerator<T>.   - Example: When would you use HashSet<T> instead of List<T>?

  • LINQ (Language Integrated Query):   - Where, Select, OrderBy, GroupBy, and Join.   - Example: Write a LINQ query to filter a list of users by age.

  • Async/Await and Multithreading:   - async/await, Task, Task<T>, and ValueTask.   - Example: Explain the difference between asynchronous and synchronous methods.

  • Exception Handling:   - try/catch/finally, throw, and custom exceptions.

  • Delegates, Events, and Lambdas:   - Func<T>, Action<T>, and event-driven programming.   - Example: How do you implement an event in C#?

Common Interview Questions: ​

  • What is the difference between string and StringBuilder?
  • Explain boxing and unboxing in C#.
  • What is the purpose of readonly in C#?
  • How do you implement operator overloading?

2. ASP.NET Core ​

ASP.NET Core is the primary framework for building backend services in .NET. Focus on key concepts and best practices.

Key Topics to Master: ​

  • MVC Architecture:   - Controllers, actions, views, and Razor syntax.   - Example: How does ASP.NET Core handle routing?

  • Dependency Injection (DI):   - Services registration (AddTransient, AddScoped, AddSingleton).   - Example: When would you use AddSingleton vs. AddTransient?

  • Middleware and Filters:   - Use(), Map(), and UseRouting() in the pipeline.   - Filters: ActionFilter, ResultFilter, ExceptionFilter.

  • Routing and Attribute Routing:   - [Route], [HttpGet], [HttpPost], and route constraints.

  • Authentication and Authorization:   - JWT, OAuth2, and AddAuthentication()/AddAuthorization().

  • Performance Optimization:   - Caching (IMemoryCache, IDistributedCache).   - Minification and bundling of static files.

Common Interview Questions: ​

  • What is the difference between ASP.NET Core and classic ASP.NET?
  • How does dependency injection work in ASP.NET Core?
  • Explain the middleware pipeline in ASP.NET Core.
  • How do you handle cross-origin requests (CORS) in ASP.NET Core?

3. Entity Framework Core (EF Core) ​

EF Core is the ORM (Object-Relational Mapper) for .NET. Be prepared to discuss its features and best practices.

Key Topics to Master: ​

  • Entity Classes and DbContext:   - Mapping entities to database tables.   - Example: How do you configure a one-to-many relationship using Fluent API?

  • LINQ to Entities:   - Querying the database using LINQ.   - Example: What is the difference between ToList() and ToListAsync()?

  • Migrations:   - Add-Migration, Update-Database, and Enable-Migrations.

  • Eager Loading, Lazy Loading, and Explicit Loading:   - Include(), Load(), and AsNoTracking().

  • Performance Tips:   - Avoiding N+1 queries with Include() and Select().

Common Interview Questions: ​

  • What is the difference between Entity Framework and Entity Framework Core?
  • How do you handle many-to-many relationships in EF Core?
  • What is change tracking in EF Core?
  • What is the purpose of SaveChanges() and SaveChangesAsync()?

4. Advanced C# and .NET Concepts ​

Be ready to discuss advanced topics and modern practices.

Key Topics: ​

  • async/await and Task-based Asynchronous Programming:   - Avoid blocking threads with ConfigureAwait(false).   - Example: How do you handle exceptions in async methods?

  • Memory Management and Garbage Collection:   - Generations (Gen 0, Gen 1, Gen 2), IDisposable, and using statements.

  • LINQ to Objects vs. LINQ to Entities:   - Differences in query execution and performance.

  • Design Patterns:   - Repository, Unit of Work, and Dependency Injection.

  • Performance Optimization:   - Profiling with Application Insights, MiniProfiler, or Visual Studio Diagnostics.

  • .NET 6/7 Features (if applicable):   - Minimal APIs, Blazor, gRPC, and ASP.NET Core Hosting Models.

Common Interview Questions: ​

  • What is ConfigureAwait(false) and when should it be used?
  • How does garbage collection work in .NET?
  • What is the difference between IEnumerable<T> and IQueryable<T>?
  • How do you implement a custom middleware in ASP.NET Core?

5. System Design and Architecture ​

Full-stack engineers often need to design scalable and maintainable systems. Be prepared to discuss:

Key Topics: ​

  • RESTful API Design:   - HTTP methods, status codes, and resource naming.

  • API Versioning:   - Query string (e.g., /api/v1/users) vs. URL path (e.g., /api/users/v1).

  • Error Handling and Logging:   - Global exception filters, Serilog, or NLog.

  • Caching Strategies:   - In-memory caching, Redis, and CDN.

  • Database Design:   - Normalization, indexing, and query optimization.

  • Scalability and Microservices:   - Horizontal scaling, load balancing, and API gateways.

Common Interview Questions: ​

  • How would you design a RESTful API for a social media platform?
  • What are the trade-offs between monolithic and microservices architecture?
  • How do you handle high traffic in an ASP.NET Core application?
  • What is the difference between stateless and stateful services?

6. Practical Tips for the Interview ​

  • Practice Coding Challenges:   - Use platforms like LeetCode, HackerRank, or CodinGame to solve C#-specific problems.
  • Whiteboard or Code on a Shared Screen:   - Explain your thought process step-by-step.
  • Ask Clarifying Questions:   - If the problem is ambiguous, ask for examples or constraints.
  • Discuss Trade-offs:   - For example, when choosing between List<T> and Dictionary<TKey, TValue>, explain the pros and cons.
  • Know the Latest .NET Features:   - Be familiar with .NET 6/7 features like Minimal APIs, gRPC, and Blazor.

7. Resources to Prepare ​