When preparing for a .NET Core interview, it’s important to not only have hands-on experience but also understand the key concepts and terminologies that employers are likely to ask about. .NET Core is an open-source, cross-platform framework developed by Microsoft, and it’s one of the most popular frameworks for building modern web applications. In this blog, we will walk through the top 10 .NET Core interview questions that every developer should know to land their next job.
1. What is .NET Core, and how is it different from the .NET Framework?
Answer: .NET Core is a cross-platform, open-source framework for building modern applications, whereas the traditional .NET Framework is Windows-only. The key differences include:
- Cross-platform compatibility: .NET Core supports Windows, Linux, and macOS.
- Performance: .NET Core is optimized for better performance.
- Modularity: .NET Core is highly modular, meaning you can include only the components you need.
2. Explain the concept of Dependency Injection in .NET Core.
Answer: Dependency Injection (DI) is a design pattern that allows you to inject objects into classes, making the code more modular and easier to test. .NET Core has built-in support for DI, enabling better separation of concerns and flexibility.
3. What is the role of the Startup.cs file in a .NET Core application?
Answer: The Startup.cs file is crucial in setting up the application’s request pipeline and configuring services (like database connections, authentication, etc.). It contains two main methods:
ConfigureServices: Configures services and dependencies.Configure: Defines the HTTP request pipeline.
4. What are middleware components in .NET Core?
Answer: Middleware in .NET Core is software that is assembled into an application pipeline to handle requests and responses. Examples include logging, authentication, and error handling middleware. These components can be added in the Configure method of the Startup.cs file.
5. What is the Entity Framework Core (EF Core)?
Answer: Entity Framework Core is an Object-Relational Mapper (ORM) for .NET Core, which allows developers to interact with databases using .NET objects. It supports multiple database providers and allows developers to use LINQ queries to interact with the data.
6. How does routing work in .NET Core MVC?
Answer: Routing in .NET Core MVC is a mechanism to map incoming requests to controller actions. Routes can be defined using attributes or convention-based patterns in the Configure method of the Startup.cs file.
7. What is the difference between IActionResult and ActionResult in .NET Core?
Answer: Both IActionResult and ActionResult are used in controllers to represent the result of an action. However:
IActionResultis an interface that can return any result type (e.g.,OkResult,NotFoundResult).ActionResultis a base class that can return more specific result types, making it more flexible in certain cases.
8. What is the purpose of the appsettings.json file in .NET Core?
Answer: appsettings.json is a configuration file used to store application settings, such as database connections and API keys. These values are read at runtime and can be used throughout the application.
9. What is the difference between .NET Core and ASP.NET Core?
Answer: .NET Core is the framework that powers cross-platform application development, while ASP.NET Core is a web framework built on top of .NET Core, used specifically for building web applications and APIs.
10. Explain the concept of a Web API in .NET Core.
Answer: A Web API in .NET Core is a service that allows applications to communicate over HTTP. It follows the RESTful architecture and allows clients to interact with data and services. You can build a Web API in .NET Core using controllers and actions.
FAQ’s Section
- Q: What is .NET Core?
A: .NET Core is a cross-platform, open-source framework used for building modern applications. It is modular and supports different operating systems like Windows, Linux, and macOS. - Q: Why is Dependency Injection important in .NET Core?
A: DI helps in achieving loose coupling, making the code more testable and maintainable. .NET Core has built-in support for DI, which simplifies application configuration and management. - Q: What is the role of the Startup.cs file?
A: TheStartup.csfile defines the application’s startup logic, including the configuration of services and middleware components that manage the request pipeline. - Q: How does routing work in .NET Core?
A: Routing in .NET Core maps HTTP requests to controller actions based on route patterns defined in the application’s configuration or using attributes in the controller. - Q: Can you explain Entity Framework Core (EF Core)?
A: EF Core is an Object-Relational Mapper (ORM) that allows developers to query and manipulate data in a database using .NET objects, without needing to write SQL queries.