Top ASP.NET C# Interview Questions for Freshers
Landing your first job as an ASP.NET C# developer can be challenging. Interviewers often focus on fundamental concepts to assess your understanding of the framework and your problem-solving abilities. Below are some commonly asked ASP.NET C# interview questions and their answers to help you prepare.
1. What is ASP.NET?
ASP.NET is a web framework developed by Microsoft for building dynamic web applications, web services, and websites. It allows developers to build web apps using .NET and C#.
2. Explain the ASP.NET Page Life Cycle.
The ASP.NET page life cycle includes the following stages:
- Initialization: Page properties such as Request and Response are set.
- Loading: During this phase, controls on the page are loaded.
- Postback Event Handling: Events triggered by user actions are handled.
- Rendering: The page's HTML is generated and sent to the client.
- Unloading: Final cleanup is performed.
3. What is the difference between ASP.NET Web Forms and MVC?
Web Forms: Based on event-driven development with a drag-and-drop interface and view state.
MVC (Model-View-Controller): Focuses on a clear separation of concerns, providing more control over HTML and using RESTful URLs.
4. What are ASP.NET Server Controls?
Server controls are components on an ASP.NET page that are executed on the server-side. They provide functionality such as text boxes, buttons, and drop-down lists. Examples include <asp:TextBox>, <asp:Button>, and <asp:GridView>.
5. Explain ViewState in ASP.NET.
ViewState is used to preserve the state of server-side controls between postbacks. It stores the state in a hidden field on the page in an encoded format.
6. What is the Global.asax file?
The Global.asax file, also known as the ASP.NET application file, contains code that responds to application-level events, such as Application_Start, Session_Start, and Application_End.
7. How can you manage state in ASP.NET?
State management in ASP.NET can be achieved using:
- Client-Side: ViewState, Cookies, Query Strings
- Server-Side: Session State, Application State, Cache
8. What is the difference between Authentication and Authorization?
Authentication: The process of verifying the identity of a user (e.g., using credentials like username and password).
Authorization: The process of determining whether a user has permission to perform a certain action or access a resource.
9. What are HTTP Handlers in ASP.NET?
HTTP Handlers are components that process individual HTTP requests made to an ASP.NET application. They handle requests for specific types of content, such as .aspx pages, images, or XML files.
10. What is ADO.NET?
ADO.NET is a set of classes in the .NET Framework that facilitates data access from various data sources, such as databases. It is used to connect to databases, execute commands, and retrieve results.
11. What are Master Pages in ASP.NET?
Master Pages in ASP.NET provide a template for other pages in the application, ensuring a consistent layout and design across multiple pages. A Master Page contains the static content (e.g., header, footer) while the Content Pages provide the dynamic content. This allows developers to maintain a uniform look and feel across the entire application.
12. What is the purpose of the Web.config file in ASP.NET?
The Web.config file is used to configure the settings of an ASP.NET application. It contains key-value pairs and sections that define how the application should behave, including settings for authentication, authorization, database connections, session management, and custom error handling. The Web.config file is XML-based and can be modified to adjust the configuration without recompiling the application.
13. Explain the concept of Postback in ASP.NET.
Postback refers to the process of submitting an ASP.NET page to the server for processing. When a user performs an action that triggers a server-side event (e.g., clicking a button), the page is sent back to the server, the event is processed, and the page is re-rendered. This is a key concept in Web Forms development, where the state of the page is maintained across postbacks using mechanisms like ViewState.
14. What is the difference between Server.Transfer and Response.Redirect?
Server.Transfer: Transfers the request from one page to another on the server without making a round-trip to the client. The URL in the browser does not change, making it faster but less transparent to the user.
Response.Redirect: Redirects the client's browser to a different URL, causing a round-trip to the server. The URL in the browser changes, which is more user-friendly but slightly slower due to the additional HTTP request.
15. How does ASP.NET handle errors?
ASP.NET handles errors using the try-catch blocks in code and by configuring custom error pages in the Web.config file. The custom error settings in the Web.config file allow developers to redirect users to a specific error page based on the type of error (e.g., 404 Not Found, 500 Internal Server Error). Additionally, the Application_Error method in the Global.asax file can be used to handle unhandled exceptions globally.
16. What are HTTP Modules in ASP.NET?
HTTP Modules are components that participate in the request and response pipeline of an ASP.NET application. They are invoked on every request made to the application and can be used to preprocess requests, add custom headers, implement authentication, and more. Common examples of HTTP Modules include FormsAuthenticationModule and UrlAuthorizationModule.
17. Explain the role of the Application Pool in IIS for ASP.NET.
An Application Pool in IIS (Internet Information Services) is a container that isolates web applications from each other. Each application pool runs independently, meaning that issues in one application do not affect others. This isolation helps improve security, reliability, and performance. ASP.NET applications run within the context of an application pool, and administrators can configure settings such as recycling and idle timeout for each pool.
18. What is LINQ in C# and how is it used in ASP.NET?
LINQ (Language-Integrated Query) is a feature in C# that allows developers to write queries directly within the code, using syntax similar to SQL. In ASP.NET, LINQ can be used to query collections, databases (via LINQ to SQL or Entity Framework), XML documents, and more. LINQ enhances readability and maintainability of code by allowing developers to use familiar query operations like select, where, order by, etc., directly within C#.
19. How does ASP.NET MVC differ from ASP.NET Core MVC?
ASP.NET MVC is a web application framework that provides a Model-View-Controller architecture for building web applications. ASP.NET Core MVC, on the other hand, is a cross-platform, high-performance framework that is part of ASP.NET Core. It also follows the MVC pattern but offers several improvements over ASP.NET MVC, including better performance, cross-platform support, dependency injection, and a more modular architecture. ASP.NET Core MVC is the recommended framework for new projects.
20. What are Bundling and Minification in ASP.NET?
Bundling and Minification are techniques used in ASP.NET to optimize web applications by reducing the number of HTTP requests and the size of CSS and JavaScript files. Bundling combines multiple files into a single file, while minification removes unnecessary characters (like whitespace and comments) from the code, reducing file size. These techniques help improve page load times and overall performance of the web application.
