- What is .NET?
Answer: .NET is a free, cross-platform, open-source framework developed by Microsoft for building various types of applications, including web, desktop, mobile, cloud, and IoT applications.
2. What are the key components of the .NET framework?
Answer: The key components of the .NET framework include the Common Language Runtime (CLR), the .NET Class Library, and various programming languages such as C#, Visual Basic .NET (VB.NET), and F#.
3. What is the Common Language Runtime (CLR)?
Answer: The CLR is the runtime environment in .NET that manages memory, executes code, handles exceptions, and provides other services required by applications. It also performs automatic memory management through garbage collection.
4. Explain the differences between .NET Framework, .NET Core, and .NET 5/6.
Answer: .NET Framework is the traditional framework for building Windows applications. .NET Core is a cross-platform and open-source framework for building modern web, desktop, and cloud applications. .NET 5/6 is the unified platform that combines the best features of .NET Framework, .NET Core, and Xamarin.
5. What is ASP.NET Core?
Answer: ASP.NET Core is an open-source web framework for building modern web applications and services. It is cross-platform, supports cloud-based hosting, and offers improved performance compared to previous versions of ASP.NET.
6. What are the advantages of using ASP.NET Core over ASP.NET MVC?
Answer: Some advantages of ASP.NET Core over ASP.NET MVC include improved performance, cross-platform support, better modularity and dependency injection, built-in support for modern web development features like Web API and SignalR, and easier integration with client-side frameworks like Angular and React.
7. Explain the concept of Dependency Injection (DI) in .NET Core.
Answer: Dependency Injection is a design pattern used to implement inversion of control (IoC) in .NET Core applications. It allows classes to receive their dependencies from external sources rather than creating them internally. This improves code maintainability, testability, and scalability.
8. What is Entity Framework Core?
Answer: Entity Framework Core (EF Core) is an open-source object-relational mapping (ORM) framework for .NET Core applications. It simplifies data access by allowing developers to work with databases using strongly typed .NET objects.
9. Explain the concept of Middleware in ASP.NET Core.
Answer: Middleware in ASP.NET Core is software components that are added to the request pipeline to handle requests and responses. It sits between the client and the server and can perform tasks such as authentication, authorization, logging, error handling, and more.
10. How do you handle asynchronous programming in .NET Core?
Answer: Asynchronous programming in .NET Core is typically handled using async/await keywords, which allow methods to run asynchronously without blocking the calling thread. This improves application responsiveness and scalability by allowing the thread to be released while waiting for asynchronous operations to complete.
Interview Questions for API Developers
- What is ASP.NET Web API?
Answer: ASP.NET Web API is a framework provided by Microsoft for building HTTP services that can be consumed by a wide range of clients, including web browsers, mobile devices, and IoT devices.
2. What are the key features of ASP.NET Web API?
Answer: Key features of ASP.NET Web API include support for HTTP protocol methods (GET, POST, PUT, DELETE), content negotiation, model binding and validation, routing, filters, dependency injection, and testing support.
3. Explain the difference between ASP.NET Web API and WCF (Windows Communication Foundation).
Answer: ASP.NET Web API is primarily used for building HTTP-based services (RESTful services) that are lightweight, easy to consume, and ideal for building applications that run over HTTP. WCF, on the other hand, is a broader framework for building distributed applications and supports various communication protocols, including HTTP, TCP, and MSMQ.
4. What is HTTP content negotiation in ASP.NET Web API?
Answer: HTTP content negotiation is the process of selecting the most appropriate representation of a resource based on the client’s preferences. In ASP.NET Web API, content negotiation is typically performed based on the Accept header in the HTTP request, and it allows clients to specify their preferred content type (e.g., JSON, XML) and language.
5. What is attribute routing in ASP.NET Web API?
Answer: Attribute routing is a feature introduced in ASP.NET Web API 2 that allows developers to define routing rules directly on controller methods and actions using attributes. This provides more flexibility and control over the routing configuration compared to convention-based routing.
6. How do you handle exceptions in ASP.NET Web API?
Answer: Exceptions in ASP.NET Web API can be handled using exception filters, global error handling middleware, or by implementing custom exception handling logic within the controllers. Additionally, ASP.NET Web API provides built-in support for returning appropriate HTTP status codes and error messages in response to exceptions.
7. What is CORS (Cross-Origin Resource Sharing) and how do you enable it in ASP.NET Web API?
Answer: CORS is a security feature implemented by web browsers to restrict cross-origin HTTP requests initiated from scripts. In ASP.NET Web API, CORS can be enabled by installing the Microsoft.AspNet.WebApi.Cors package and configuring CORS policies in the WebApiConfig class or using the EnableCors attribute on controllers or actions.
8. How do you implement authentication and authorization in ASP.NET Web API?
Answer: Authentication and authorization in ASP.NET Web API can be implemented using various approaches, including basic authentication, token-based authentication (e.g., JWT), OAuth, and OAuth2. Additionally, ASP.NET Web API provides built-in support for integrating with ASP.NET Identity for user authentication and role-based authorization.
9. What are the advantages of using DTOs (Data Transfer Objects) in ASP.NET Web API?
Answer: DTOs are used to encapsulate data transferred between the client and the server in ASP.NET Web API applications. Advantages of using DTOs include decoupling the API from the underlying domain model, reducing over-fetching and under-fetching of data, improving performance, and enhancing security by controlling the data exposed to clients.
10. How do you test ASP.NET Web API controllers?
Answer: ASP.NET Web API controllers can be tested using various techniques, including unit testing with mocking frameworks (e.g., Moq), integration testing using tools like Postman or Swagger, and automated testing using frameworks like NUnit or xUnit.