Ace Your ASP.NET Interview: Frequently Asked Questions and Answers

Prepare for your next ASP.NET interview with this comprehensive guide to frequently asked questions. This resource covers core concepts, common techniques, and best practices, helping you confidently demonstrate your ASP.NET expertise.

Top ASP.NET Interview Questions and Answers

Fundamental ASP.NET Concepts

1. What is ASP? Active Server Pages (ASP), also known as classic ASP, is a server-side technology from Microsoft for creating dynamic web pages using scripting languages.
2. What is ASP.NET? ASP.NET is a framework for building web applications and services using .NET languages (C#, VB.NET). It offers improved performance compared to classic ASP.
3. ASP vs. ASP.NET: ASP is interpreted; ASP.NET is compiled. ASP uses VBScript; ASP.NET uses .NET languages.
4. What is IIS? Internet Information Services (IIS) is a web server from Microsoft used to host ASP.NET applications.
5. IIS Usage: IIS hosts web applications, handles request/response cycles, and provides services like SMTP (email) and FrontPage server extensions.
6. Multilingual Website: A website offering content in multiple languages.
7. Caching: Storing frequently accessed data in memory for faster retrieval.
8. Caching Requirements: Carefully select items to cache, considering the overhead. Suitable for data that doesn't change frequently.
9. Advantages of ASP.NET: Scalability, compiled code, user authentication, language support, easy configuration and deployment, caching, and strong coding standards.
10. Postback in ASP.NET: An HTTP POST request from a client to the server for the same page, refreshing the page.
11. IsPostBack Property: Used to check if a page is being loaded for the first time or if it's a postback.
12. Identifying Postbacks: Check the IsPostBack property of the Page object.
13. Parent Class of Web Server Controls: System.Web.UI.Control
14. Web Forms vs. MVC: Web Forms uses a page controller; MVC uses a front controller.
15. GET vs. POST Methods:

    Feature	GET	POST
    Data in URL	Yes	No
    Security	Less secure	More secure
    Speed	Faster	Slower
    Data Amount	Limited	Larger
    Default	Yes (often)	No (must be explicitly specified)

16. Session vs. Application Object: Session object stores data for a single user's session; application object stores data accessible to all users.
17. Trace vs. Debug: Trace is for both debug and release builds; Debug is only for debug builds.
18. Client-Side vs. Server-Side Validation: Client-side validation (JavaScript) happens in the browser; server-side validation happens on the server.
19. File-Based vs. Key-Based Dependency: File-based dependency is stored in a file; key-based dependency refers to another cached item.
20. Globalization vs. Localization: Globalization separates language-specific elements; localization adapts the application for a specific language.
21. Page Theme vs. Global Theme: Page themes apply to specific pages; global themes apply to the entire application.
22. Early Binding vs. Late Binding: Early binding resolves method calls at compile time; late binding at runtime.
23. Server-Side vs. Client-Side Scripting: Server-side scripts run on the server; client-side scripts run in the browser.
24. Signing Out of Forms Authentication: Use FormsAuthentication.SignOut().
25. Displaying Validation Messages: Use the ValidationSummary control.
26. Authentication vs. Authorization: Authentication verifies user identity; authorization checks access permissions.
27. ViewState: Stores page data between postbacks.
28. ViewState Storage: Stored in an HTML hidden field.
29. Response.Write() vs. Response.Output.Write(): Response.Write() for plain text; Response.Output.Write() for formatted output.
30. Configuration Files: Web.config (application level); Machine.config (machine level).

Advanced ASP.NET Concepts

1. What's the difference between Web.config and Machine.config? Web.config is specific to a web application; Machine.config applies to the entire server. There can be multiple Web.config files, but only one Machine.config file.
2. What is MVC? Model-View-Controller (MVC) is a design pattern separating business logic (Model), presentation (View), and user interaction (Controller).
3. Built-in ASP.NET Objects: Application, Session, Context, Request, Response, Server, Trace.
4. Role-Based Security: Assigns privileges to roles; users are assigned roles, limiting their access based on their roles.
5. What is a Cookie? A small piece of data stored on the client's computer. Types include session (temporary) and persistent cookies.
6. Default Cookie Timeout: 30 minutes.
7. Disabling Cookies: Set the Cookie.Discard property to true.
8. Protocol for Calling Web Services: HTTP.
9. Web Service File Extension: .asmx
10. HTML Server Controls: Standard HTML elements with added properties and events for server-side access (using runat="server").
11. Global.asax File: Handles application-level events and variables.
12. Event Bubbling: Child controls send events up to their parent controls.
13. Page Theme vs. Global Theme: Page themes apply to individual pages; global themes apply to the entire application.
14. Early Binding vs. Late Binding: Early binding (non-virtual methods) happens at compile time; late binding (virtual methods) at runtime.
15. Server-Side vs. Client-Side Scripting: Server-side scripts run on the server; client-side scripts (JavaScript, VBScript) run in the browser.
16. Signing Out of Forms Authentication: Use FormsAuthentication.SignOut().
17. Displaying Validation Messages: Use the ValidationSummary control.
18. Authentication vs. Authorization: Authentication verifies identity; authorization checks permissions.
19. Session Object: Stores data specific to a user's session.
20. ViewState: Stores page data between postbacks.
21. ViewState Storage: An HTML hidden field.
22. Response.Write() vs. Response.Output.Write(): Response.Write() for plain text; Response.Output.Write() for formatted output.
23. Types of Configuration Files: Web.config (application); Machine.config (machine).