ASP.NET Interview Questions

ASP is Active Server Pages is a useful tool by Microsoft to create user friendly web pages. This is also called as classic ASP. This is equipped by different scripted languages that helps in creating dynamic webpages that can be run on any browser.

ASP.NET is highly beneficial over ASP. It is the next level of the ASP framework. The advantages of ASP.NET are given here. ASP.NET has high scalability, good third-party control, language support, reliable user authentication, and compiled codes. Using ASP.NET can also make configuration and deployment of application very easy. With ASP.NET, the user needs strict coding requirements. This helps the application to strike a balance between the server and compatibility. Additionally, there is an object and page caching too. Thus, ASP.NET helps us build quality web pages and web applications that will be very useful for companies.

Validation in ASP.NET is an important thing as it is helpful in saving storage space. The validators of ASP.NET validate the input data before storing them. This helps in removing the unauthenticated, useless contrasting and contradicting data. They are removed and don't get stored. The validators of ASP.NET are RangeValidator, RequiredFieldValidator, CompareValidator, RegularExpressionValidator, CustomerValidator, and ValidationSummary.

Every page created in ASP.NET goes through a series of stages. This is called the life cycle of the page in ASP.NET and the different stages are given here.

1. Page request: Whenever the user requests a page, ASP.NET analyses if it should be compiled or otherwise serve it from a cache. This is the first step/process of the page's lifecycle.
2. Start: Every page has a beginning condition and this step sets them for one particular page.
3. Initialization: In this phase, all the on-page controls are initiated and the themes start getting applied.
4. Load: The control properties are set using view state and control state properties.
5. Post back event handling: The input given by the user is handled whenever required.
6. Rendering: While using ASP.NET, it can save the view state for your page. It then writes the output of the rendering into the output stream.
7. Unload: Once all the pages are rendered, they are sent to the client. Therefore, ASP.NET unloads all input page properties and then performs clean up.

Session State Modes uses WebForms to solve some problems like reliability and scalability. It can be stored on in different places and depending upon that, ASP.NET supports the following session state modes.

• InProc mode: This is the default mode in ASP.NET and it is stored in the web server memory.
• StateServer mode: This follows a process called the ASP.NET State Service. This is where the Session State is stored. When this app gets restarted, the Session State gets permanently stored or preserved on it.
• SQLServer mode: This stores the Session State on SQL Database. It gets preserved when the web app is restarted.
• Custom mode: The developer can set up/provide a customized storage provider.
• Off mode: This disables the Session State mode.

This feature of ViewState in ASP.NET helps you to store values inputted on the page before it gets submitted on the server. Once this is posted on the server, the data on ViewState is restored. This is stored on the HTML hidden field.

A PostBack is when the user takes some action on the web page like filling a form or enrolling for newsletters, this information given on the page is sent to the server through a Post. This is accomplished by an HTTP POST mechanism in ASP.NET. Once the task by the user is complete, this sends the complete page again to the server to refresh it for the next user. This makes web pages convenient.

Caching is a quick technique that helps in storing the frequently used information in the memory. This helps you access them more quickly whenever needed. The user should be clear on which information to cache. This is because caching all information leads to overheads. It is advisable to cache data that does not change frequently and is also used frequently used on the web.

A cookie is a piece of information that gets stored on the client side. It can either be temporary or permanent. A temporary or session cookie is valid only for one session. While a permanent cookie is valid for many sessions. There is also a default timeout for a cookie which is 30 minutes.

One can also turn off cookies on a page in a website. This is done using the Cookie Discard property. The discard flag is determined by the server using get or set options. So when this property is set to true, the Cookie does not get saved to the hard disk of the user at the end of one session.

The built-in objects in ASP.NET are the application, session, context, request, response, server, and trace. These are the major functionalities of ASP.NET that make it suitable for web applications.

ASP.NET has two types of configuration files. They are Web config files and Machine config files.

• The web config files are application level configuration and are specific to the web application alone. One application may contain more than one web config. It is represented as Web.config.
• Machine config files are machine level configuration, so they are specific to the machine or server. Only one machine config file can be present for one web application. It is represented as Machine.config.

ASP.NET is used to create web services and web applications. This is a specification given by Microsoft. ASP.NET is one of the most successful parts of the .NET framework. It is very compatible with all .NET languages like C#, Visual Basic etc. Using these languages you can create several web applications based on ASP.NET framework. This is much better than normal scripting languages.

The major difference between Session Object and Application Object are as follows -