The ASP.Net Web API framework allows you to create HTTP services that can be accessed from any client-server, including browsers and mobile phones. 

Learning ASP.Net Web API Concepts and applying for a position as an ASP.Net Web API developer has many perks 一 from building RESTful HTTP-based services to services that support only HTTP protocol; the possibilities are many. As a result, the ASP.Net web API jobs are always available and recruiters are always on the hunt. 

To help you get in the good books of recruiters, we’ve compiled a list of questions you should prepare for when applying for ASP.Net web API jobs. 

The following are some of the most frequently asked Web API interview questions. We recommend that you delve deeper into each question for further understanding of each of them, helping you tackle follow-up questions as well. 

Top 10 ASP.Net Web API Interview Questions 

1. What is the significance of a Web API?

A web API is a service that allows you to get data or information from a server. It is necessary for the expansion of a company. Additionally it 一

• Provides a data access interface for both webpages and client applications.
• Supports a variety of text formats, including XML and JSON.

2. Is it true that WCF has been replaced with ASP.NET Web API?

ASP.NET Web API has not taken the place of WCF. In actuality, it’s a different approach to creating non-SOAP services, such as plain XML or JSON strings.

3. What are the most common Web API return types?

The following values can be returned by a Web API controller action:

• Void – It will return an empty string.
• HttpResponseMessage — This method transforms the response into an HTTP message.
• IHttpActionResult – creates a HttpResponseMessage by calling ExecuteAsync internally.
• Other types — The serialised return value can be written into the response body.

4. Which .NET frameworks are compatible with Web API?

Web API is supported by NET 4.0 and later versions.

5. How can you make the ASP.NET Web API more secure?

The ASP.NET Web API comes up with in-built Authentication and Authorization custom attributes which can be applied to individual controllers or globally to all controllers. This will act as a guard to access the APIs.

6. What are HTTP status codes, and what do they mean?

The three-digit numbers in the server response are known as HTTP Status Codes. Each number has a distinct meaning. HTTP Status Codes are divided into five types.

1. Informational responses (100–199)
2. Successful responses (200–299)
3. Redirection messages (300–399)
4. Client error responses (400–499)
5. Server error responses (500–599)

These response status codes indicate whether a specific HTTP request has been successfully completed. 

7. Describe the exception filters used in the ASP.NET Web API.

By designing an exception filter, you may customise how Web API handles exceptions. When a controller method throws an unhandled exception that isn’t a HttpResponseException exception, an exception filter is run. 

8. In ASP.NET Web API, what is Media-Type Formatter?

JsonMediaTypeFormatter (handle JSON format) and XmlMediaTypeFormatter (handle XML format) are both inherited from the Media-Type formatter abstract class. The Media-Type formatter classes are in charge of serialising the response data in the format requested by the client. This is broadly known as content negotiation in the RESTful world.

9.  What is a Query String in ASP.Net?

A query string is a string (a collection of characters) that is passed on as part of the address or URL in any web browser. A question mark (?) is frequently used to separate this.

The syntax of how to read query string is:

Request.QueryString(variable)[(index).count]

10. When should you use ASP.Net web API instead of WCF?

It is entirely dependent on the situation. If you only want HTTP-based services, use ASP.NET Web API, which has a lightweight architecture and is suitable for devices with limited bandwidth. WCF can also be used to establish REST services, but it takes a lot of configuration. WCF is the preferable option if you require a service that supports several transport protocols such as HTTP, UDP, TCP, and so forth.

There you have it! Top 10 questions that’ll help you get an idea of the types of questions that will be asked and the topics you need to prepare for. As mentioned earlier, be sure you read up more about these ASP.Net Web API concepts to be ready for any and all follow-up questions. 

If you need assistance in learning ASP.Net Web API concepts, reach out to Skill-House! Learn and apply new concepts under expert guidance and work on real-time projects to gain industry experience. Register now and start planning for your placement interviews!