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ASP.Net Interview Questions & Answers

Basics of ASP.NET:

  1. What is ASP.NET?

    • Answer: ASP.NET is a web development framework by Microsoft for building dynamic web applications, websites, and web services.

  2. Explain the difference between ASP.NET Web Forms and ASP.NET MVC.

    • Answer: Web Forms follows a page-centric model with server controls, while MVC is based on the Model-View-Controller pattern, providing more control over the HTML and JavaScript.

  3. What is the Page Life Cycle in ASP.NET?

    • Answer: The Page Life Cycle represents the stages a web page goes through, including initialization, loading, rendering, and unloading.

  4. What is ViewState, and how is it used in ASP.NET Web Forms?

    • Answer: ViewState is used to persist state information across postbacks in ASP.NET Web Forms. It stores data on the client side and helps in maintaining the state of controls.

  5. Explain the role of the Global.asax file in ASP.NET.

    • Answer: Global.asax is the ASP.NET application file where events like Application_Start, Application_End, Session_Start, and Session_End are handled.

ASP.NET MVC:

  1. What is ASP.NET MVC, and how does it differ from Web Forms?

    • Answer: ASP.NET MVC is a framework for building web applications following the Model-View-Controller pattern. It provides more control over the HTML and allows separation of concerns.

  2. Explain the Model-View-Controller (MVC) pattern in ASP.NET.

    • Answer: MVC separates an application into three components: Model (data and business logic), View (presentation layer), and Controller (handles user input and updates the Model and View).

  3. What is Routing in ASP.NET MVC?

    • Answer: Routing maps URLs to controller actions in ASP.NET MVC, allowing for clean and user-friendly URLs.

  4. What is the Razor view engine in ASP.NET MVC?

    • Answer: Razor is a view engine in ASP.NET MVC that allows embedding server-based code into the HTML markup using C# or VB.NET.

  5. Explain the purpose of TempData in ASP.NET MVC.

    • Answer: TempData is used to pass data from the current request to the next request, especially during redirects. It stores data for a short duration.

ASP.NET Core:

  1. What is ASP.NET Core, and how is it different from ASP.NET?

    • Answer: ASP.NET Core is a cross-platform, high-performance, and open-source framework for building modern, cloud-based, and internet-connected applications. It is a modular and leaner version compared to ASP.NET.

  2. Explain Dependency Injection in ASP.NET Core.

    • Answer: Dependency Injection is a design pattern where a class receives its dependencies from an external source. ASP.NET Core provides a built-in DI container for managing and injecting dependencies.

  3. How does ASP.NET Core support cross-platform development?

    • Answer: ASP.NET Core is designed to be cross-platform and can run on Windows, Linux, and macOS. It is not tied to a specific operating system or web server.

  4. What is Kestrel in ASP.NET Core?

    • Answer: Kestrel is a cross-platform, lightweight, and open-source web server designed to be used with ASP.NET Core applications.

  5. Explain the concept of Middleware in ASP.NET Core.

    • Answer: Middleware in ASP.NET Core is components that are added to the request pipeline to handle requests and responses. Each middleware component processes the request and can modify the response.

ASP.NET Web API:

  1. What is ASP.NET Web API, and how is it different from ASP.NET MVC?

    • Answer: ASP.NET Web API is a framework for building HTTP services that can be consumed by a variety of clients, including web browsers and mobile devices. It is specifically designed for building RESTful APIs.

  2. How can you handle Cross-Origin Requests (CORS) in ASP.NET Web API?

    • Answer: CORS can be configured in ASP.NET Web API using the EnableCors attribute or by configuring CORS in the Web.config file.

  3. What are IHttpActionResult and HttpResponseMessage in ASP.NET Web API?

    • Answer: IHttpActionResult is an interface representing an HTTP response message, and HttpResponseMessage is a class that encapsulates the HTTP response.

  4. Explain content negotiation in ASP.NET Web API.

    • Answer: Content negotiation in ASP.NET Web API is the process of selecting the most appropriate representation of a resource based on the client's request headers, such as Accept header.

  5. How can you implement versioning in ASP.NET Web API?

    • Answer: Versioning in ASP.NET Web API can be implemented using URI versioning, query string versioning, or header versioning.

Entity Framework:

  1. What is Entity Framework, and how does it work with databases?

    • Answer: Entity Framework is an Object-Relational Mapping (ORM) framework that enables developers to work with databases using .NET objects. It maps database entities to .NET objects.

  2. Explain the Code First approach in Entity Framework.

    • Answer: Code First is an approach in Entity Framework where the database is created based on the code (C# classes) rather than the other way around. Developers define classes, and EF generates the database schema.

  3. What is the purpose of DbSet in Entity Framework?

    • Answer: DbSet is a property in a DbContext class that represents a collection of entities of a particular type. It provides methods for querying, adding, updating, and deleting entities.

  4. How can you handle database migrations in Entity Framework Code First?

    • Answer: Database migrations in Entity Framework Code First are handled using the Add-Migration and Update-Database commands in the Package Manager Console (PMC) or using the dotnet ef migrations command.

  5. Explain the difference between eager loading and lazy loading in Entity Framework.

    • Answer: Eager loading loads related entities along with the main entity in a single query, while lazy loading defers the loading of related entities until they are explicitly accessed.

Security in ASP.NET:

  1. How can you implement authentication in ASP.NET applications?

    • Answer: Authentication in ASP.NET can be implemented using Forms Authentication, Windows Authentication, or external authentication providers like OAuth and OpenID Connect.

  2. Explain the concept of Cross-Site Scripting (XSS) and how to prevent it in ASP.NET.

    • Answer: XSS is a security vulnerability where attackers inject malicious scripts into web pages viewed by other users. Prevention involves proper input validation, encoding, and using AntiXSS libraries.

  3. What is Cross-Site Request Forgery (CSRF), and how can it be prevented?

    • Answer: CSRF is an attack where an unauthorized user makes a request on behalf of an authenticated user. Prevention involves using anti-forgery tokens and validating requests.

  4. How can you secure sensitive information in ASP.NET applications?

    • Answer: Sensitive

information in ASP.NET applications can be secured using techniques such as encryption, secure storage mechanisms, and protecting sensitive data in transit.

  1. Explain the Same-Origin Policy and how it relates to security in web applications.
    • Answer: The Same-Origin Policy is a security measure that restricts web pages from making requests to a different domain than the one that served the web page. It helps prevent Cross-Site Request Forgery (CSRF) and other attacks.

ASP.NET Core Middleware:

  1. Explain the concept of middleware in ASP.NET Core.

    • Answer: Middleware in ASP.NET Core is a pipeline of components that handle requests and responses. Each middleware component processes the request and can modify the response.

  2. What is the purpose of app.UseMvc() in the Configure method of Startup.cs?

    • Answer: app.UseMvc() is used to add MVC to the request processing pipeline in an ASP.NET Core application. It configures the app to use MVC middleware to handle requests.

  3. How can you create custom middleware in ASP.NET Core?

    • Answer: Custom middleware in ASP.NET Core can be created by implementing a class with a method that takes a HttpContext parameter. This class should have a reference to the next middleware in the pipeline.

  4. Explain the role of app.UseAuthentication() in ASP.NET Core middleware.

    • Answer: app.UseAuthentication() is used to add authentication middleware to the request processing pipeline in ASP.NET Core. It configures the app to use authentication for incoming requests.

  5. What is the purpose of app.UseAuthorization() in ASP.NET Core middleware?

    • Answer: app.UseAuthorization() is used to add authorization middleware to the request processing pipeline in ASP.NET Core. It configures the app to use authorization for incoming requests.

ASP.NET Core Health Checks:

  1. What are health checks in ASP.NET Core, and why are they useful?

    • Answer: Health checks in ASP.NET Core provide a way to monitor the health of an application by checking the status of its components. They are useful for identifying and resolving issues proactively.

  2. How can you implement health checks in ASP.NET Core?

    • Answer: Health checks in ASP.NET Core can be implemented by adding the AddHealthChecks method in the ConfigureServices method and configuring checks for different components.

ASP.NET Core and Docker:

  1. How can you use Docker with ASP.NET Core applications?

    • Answer: Docker can be used with ASP.NET Core by creating a Dockerfile to package the application, and a docker-compose.yml file to define services and dependencies.

  2. What are the benefits of using Docker with ASP.NET Core?

    • Answer: Benefits include consistent environments across development, testing, and production, ease of deployment, and improved scalability.

ASP.NET Core Design Patterns:

  1. Explain the Repository Pattern and its use in ASP.NET Core.

    • Answer: The Repository Pattern involves separating the logic that retrieves data from the underlying storage. It is commonly used in ASP.NET Core to decouple data access code.

  2. What is the role of the Unit of Work pattern in ASP.NET Core?

    • Answer: The Unit of Work pattern manages the transactional boundaries and ensures that a set of operations is treated as a single unit. It is often used in conjunction with the Repository Pattern.

ASP.NET Core Hosting:

  1. Explain the hosting models in ASP.NET Core.
    • Answer: ASP.NET Core supports two hosting models: In-process hosting and Out-of-process hosting. In-process hosting runs the app in the same process as the IIS worker process, while Out-of-process hosting runs the app in a separate process.

ASP.NET Core and Authentication:

  1. How can you implement authentication in ASP.NET Core?
    • Answer: Authentication in ASP.NET Core can be implemented using ASP.NET Core Identity, external providers (OAuth, OpenID Connect), or custom authentication middleware.

ASP.NET Core and Authorization:

  1. What is role-based authorization in ASP.NET Core, and how is it implemented?
    • Answer: Role-based authorization in ASP.NET Core allows you to restrict access to certain parts of an application based on the roles assigned to a user. It is implemented using attributes like [Authorize(Roles = "Admin")].

ASP.NET Core and Configuration:

  1. How does configuration work in ASP.NET Core, and what are its sources?
    • Answer: Configuration in ASP.NET Core is based on the key-value pair model. Configuration values can be sourced from various providers, including JSON files, environment variables, and command-line arguments.

ASP.NET Core and Logging:

  1. Explain the logging levels in ASP.NET Core and their significance.
    • Answer: Logging levels, such as Information, Warning, and Error, allow developers to categorize log messages based on their importance. They help in filtering and identifying issues during development and troubleshooting.

ASP.NET Core and Deployment:

  1. What are the different deployment strategies for ASP.NET Core applications?
    • Answer: ASP.NET Core applications can be deployed using strategies like self-contained deployments, Docker containers, and Azure App Service deployments.

ASP.NET Core and Entity Framework Core:

  1. How can you optimize performance when using Entity Framework Core in an ASP.NET Core application?
    • Answer: Performance optimization techniques include using proper indexing, eager loading, using raw SQL for complex queries, and monitoring and optimizing database queries.

ASP.NET Core and Testing:

  1. What are the common testing frameworks used in ASP.NET Core, and how do they differ?
    • Answer: Common testing frameworks include xUnit, NUnit, and MSTest. They differ in terms of features, syntax, and extensibility. Choose a framework based on project requirements and team preferences.

ASP.NET Core and SignalR:

  1. What is SignalR, and how is it used in ASP.NET Core?
    • Answer: SignalR is a library for adding real-time functionality to applications. In ASP.NET Core, it can be used to enable real-time communication between clients and the server.