ASP.Net Advanced Level Interview Questions & Answers

1. What is the ASP.NET Core and how does it differ from ASP.NET?
   Answer: ASP.NET Core is a cross-platform, open-source framework for building modern, high-performance web applications. Unlike traditional ASP.NET, it can run on Windows, Linux, and macOS and offers better performance and modularity.
   
   
2. Explain Dependency Injection in ASP.NET Core.
   Answer: Dependency Injection is a design pattern in ASP.NET Core used to manage the dependencies of an application. It allows you to inject services or objects into components, making code more maintainable, testable, and modular.
   
   
3. Describe the benefits and use cases of Middleware in ASP.NET Core.
   Answer: Middleware components in ASP.NET Core handle requests and responses in a pipeline. They provide a way to add cross-cutting concerns, such as authentication, routing, and logging, to your application.
   
   
4. What is the Razor Pages framework in ASP.NET Core?
   Answer: Razor Pages is a page-focused framework in ASP.NET Core that simplifies building web pages by integrating the UI and code in a single file. It’s useful for building small to medium-sized web applications.
   
   
5. How does ASP.NET Core support asynchronous programming, and why is it important?
   Answer: ASP.NET Core uses asynchronous programming to improve performance and responsiveness. It allows tasks to be executed concurrently, enabling more efficient use of server resources.
   
   
6. What are Tag Helpers in ASP.NET Core and how do they differ from HTML helpers?
   Answer: Tag Helpers are a feature in ASP.NET Core that allow you to create server-side code that renders HTML elements, making the code more readable and resembling standard HTML. They are more user-friendly than HTML helpers.
   
   
7. Explain the use of Entity Framework Core in ASP.NET Core.
   Answer: Entity Framework Core is an Object-Relational Mapping (ORM) framework for data access in ASP.NET Core. It allows you to work with databases using object-oriented code, making data access more convenient and abstracting the underlying database.
   
   
8. How does ASP.NET Core support containerization and microservices architecture?
   Answer: ASP.NET Core is designed to work seamlessly with containerization platforms like Docker. It’s also well-suited for microservices development due to its lightweight and modular architecture.
   
   
9. Describe the benefits and use of SignalR in ASP.NET Core.
   Answer: SignalR is a real-time communication library in ASP.NET Core that enables features like chat, notifications, and live updates. It’s essential for building interactive and responsive web applications.
   
   
10. What is Identity in ASP.NET Core, and how does it simplify authentication and authorization?
    Answer: Identity is a framework for handling authentication and authorization in ASP.NET Core applications. It provides user registration, login, and role-based access control out of the box.
    
    
11. Explain the concept of gRPC in ASP.NET Core.
    Answer: gRPC is a high-performance, cross-platform remote procedure call (RPC) framework for building efficient and scalable APIs in ASP.NET Core, using Protocol Buffers for serialization.
    
    
12. How do you implement and manage configuration in ASP.NET Core applications?
    Answer: Configuration in ASP.NET Core can be managed through JSON files, environment variables, and configuration providers. It allows you to centralize and customize application settings.
    
    
13. What is the Kestrel web server in ASP.NET Core, and how does it differ from IIS?
    Answer: Kestrel is a cross-platform, lightweight web server built for ASP.NET Core. It can be used as a standalone server or behind a reverse proxy like IIS or Nginx for serving ASP.NET Core applications.
    
    
14. How does ASP.NET Core handle cross-site request forgery (CSRF) protection?
    Answer: ASP.NET Core provides CSRF protection through anti-forgery tokens, which are generated and verified to prevent unauthorized actions in web applications.
    
    
15. Explain the role of distributed caching in ASP.NET Core and how it can improve application performance.
    Answer: Distributed caching helps reduce database load and improve response times by storing frequently accessed data in memory. ASP.NET Core supports distributed caching with providers like Redis and SQL Server.
    
    
16. What is the role of the Health Checks feature in ASP.NET Core, and why is it important?
    Answer: Health Checks in ASP.NET Core allow applications to report their status, making it easier to monitor and diagnose issues. It’s important for ensuring the availability and reliability of services.
    
    
17. How does ASP.NET Core support background processing and task scheduling?
    Answer: ASP.NET Core provides a built-in BackgroundService class and integration with libraries like Hangfire for background processing and task scheduling.
    
    
18. Explain the purpose and use of the HttpClient class in ASP.NET Core.
    Answer: The HttpClient class is used to make HTTP requests from an ASP.NET Core application to external services or APIs, allowing you to retrieve and send data.
    
    
19. How do you implement and secure Web APIs in ASP.NET Core, and what are the best practices?
    Answer: Web APIs in ASP.NET Core can be secured using authentication and authorization mechanisms. Best practices include using JWT tokens, role-based access control, and rate limiting.
    
    
20. Describe the differences between Razor Pages, MVC, and Web API in ASP.NET Core and when to use each.
    Answer: Razor Pages are best for simple web pages. MVC is used for more complex web applications with separate concerns, while Web API is for building RESTful APIs.
    
    
21. What is the purpose of an ASP.NET Core middleware, and how do you create custom middleware components?
    Answer: Middleware components in ASP.NET Core handle HTTP requests and responses. You can create custom middleware by implementing the InvokeAsync method and adding it to the pipeline.
    
    
22. Explain how you can implement versioning in ASP.NET Core Web APIs.
    Answer: Versioning in ASP.NET Core can be achieved by adding version information to the URL, headers, or query parameters, allowing multiple versions of the same API to coexist.
    
    
23. How do you optimize the performance of ASP.NET Core applications, and what tools are available for profiling and debugging?
    Answer: Performance optimization in ASP.NET Core involves techniques like caching, database optimization, and load balancing. Profiling and debugging can be done using tools like Visual Studio and Application Insights.
    
    
24. Describe the role of global error handling and exception logging in ASP.NET Core.
    Answer: Global error handling is essential for catching unhandled exceptions and logging errors. You can use middleware, filters, and external services for exception logging.
    
    
25. What are the best practices for securing ASP.NET Core applications, and how do you protect against common security vulnerabilities?
    Answer: Security best practices include input validation, using HTTPS, implementing strong authentication and authorization, and protecting against common vulnerabilities like SQL injection and XSS.
    
    
26. How can you implement real-time features in ASP.NET Core applications, and what technologies are commonly used for this purpose?
    Answer: Real-time features can be implemented using SignalR for WebSocket-based communication and technologies like WebSockets and Server-Sent Events for building interactive and live-updating features.
    
    
27. Explain the role of dependency injection containers and service lifetimes in ASP.NET Core.
    Answer: Dependency injection containers manage the lifetime and registration of services. ASP.NET Core provides three lifetimes: transient, scoped, and singleton, to control how services are created and shared.
    
    
28. How does ASP.NET Core handle application configuration, and what are the options for storing and managing configuration data?
    Answer: ASP.NET Core uses the IConfiguration interface to handle application configuration. Configuration data can be stored in JSON files, environment variables, or external providers like Azure Key Vault.
    
    
29. Describe the use of custom authentication schemes in ASP.NET Core for scenarios beyond username and password authentication.
    Answer: Custom authentication schemes in ASP.NET Core allow you to implement alternative authentication methods, such as social logins, two-factor authentication, and token-based authentication.
    
    
30. How can you scale and deploy ASP.NET Core applications in a production environment, and what strategies are available for high availability?
    Answer: ASP.NET Core applications can be scaled using load balancers and containerization technologies. Strategies for high availability include failover, redundancy, and disaster recovery planning.

These advanced-level ASP.NET interview questions and answers cover a wide range of topics to help you assess a candidate’s knowledge and expertise in ASP.NET development.