Important Interview questions on ASP.NET

1. Whats an assembly? Assemblies are the building blocks of .NET Framework applications; they form the fundamental unit of deployment, version control, reuse, activation scoping, and security permissions. An assembly is a collection of types and resources that are built to work together and form a logical unit of functionality. An assembly provides the common language runtime with the information it needs to be aware of type implementations. To the runtime, a type does not exist outside the context of an assembly.
2. Describe the difference between inline and code behind – which is best in a loosely coupled solution? ASP.NET supports two modes of page development: Page logic code that is written inside <script runat=server> blocks within an .aspx file and dynamically compiled the first time the page is requested on the server. Page logic code that is written within an external class that is compiled prior to deployment on a server and linked “behind” the .aspx file at run time.
3. Explain what a diffgram is, and a good use for one? A DiffGram is an XML format that is used to identify current and original versions of data elements. The DataSet uses the DiffGram format to load and persist its contents, and to serialize its contents for transport across a network connection. When a DataSet is written as a DiffGram, it populates the DiffGram with all the necessary information to accurately recreate the contents, though not the schema, of the DataSet, including column values from both the Original and Current row versions, row error information, and row order.
4. Where would you use an iHTTPModule, and what are the limitations of anyapproach you might take in implementing one? One of ASP.NET’s most useful features is the extensibility of the HTTP pipeline, the path that data takes between client and server. You can use them to extend your ASP.NET applications by adding pre- and post-processing to each HTTP request coming into your application. For example, if you wanted custom authentication facilities for your application, the best technique would be to intercept the request when it comes in and process the request in a custom HTTP module.
5. In what order do the events of an ASPX page execute. As a developer is it important to undertsand these events? Every Page object (which your .aspx page is) has nine events, most of which you will not have to worry about in your day to day dealings with ASP.NET. The three that you will deal with the most are: Page_Init, Page_Load, Page_PreRender.
6. Which method do you invoke on the DataAdapter control to load your generated dataset with data?

System.Data.Common.DataAdapter.Fill(System.Data.DataSet);

If my DataAdapter is sqlDataAdapter and my DataSet is dsUsers then it is called this way:

sqlDataAdapter.Fill(dsUsers);

7. Which template must you provide, in order to display data in a Repeater control? ItemTemplate
8. How can you provide an alternating color scheme in a Repeater control?

AlternatingItemTemplate Like the ItemTemplate element, but rendered for every other
row (alternating items) in the Repeater control. You can specify a different appearance
for the AlternatingItemTemplate element by setting its style properties.

9. What property must you set, and what method must you call in your code, in order to bind the data from some data source to the Repeater control?

You must set the DataMember property which Gets or sets the specific table in the DataSource to bind to the control and the DataBind method to bind data from a source to a server control. This method is commonly used after retrieving a data set through a database query.

10. What base class do all Web Forms inherit from?
    System.Web.UI.Page
11. What method do you use to explicitly kill a user’s session?

The Abandon method destroys all the objects stored in a Session object and releases their resources.
If you do not call the Abandon method explicitly, the server destroys these objects when the session times out.

Syntax: Session.Abandon

12. How do you turn off cookies for one page in your site?
    Use the Cookie.Discard Property which Gets or sets the discard flag set by the server. When true, this
    property instructs the client application not to save the Cookie on the user’s hard disk when a session ends.
13. Which two properties are on every validation control? ControlToValidate & ErrorMessage properties
14. How do you create a permanent cookie? Setting the Expires property to MinValue means that the Cookie never expires.
15. Which method do you use to redirect the user to another page without performing a round trip to the client? Server.transfer()
16. What is the transport protocol you use to call a Web service? SOAP. Transport Protocols: It is essential for the acceptance of Web Services that they are based on established Internet infrastructure. This in fact imposes the usage of of the HTTP, SMTP and FTP protocols based on the TCP/IP family of transports. Messaging Protocol: The format of messages exchanged between Web Services clients and Web Services should be vendor neutral and should not carry details about the technology used to implement the service. Also, the message format should allow for extensions and different bindings to specific transport protocols. SOAP and ebXML Transport are specifications which fulfill these requirements. We expect that the W3C XML Protocol Working Group defines a successor standard.
17. True or False: A Web service can only be written in .NET. False.
18. What does WSDL stand for? Web Services Description Language
19. What property do you have to set to tell the grid which page to go to when using the Pager object?
20. Where on the Internet would you look for Web services? UDDI repositaries like uddi.microsoft.com, IBM UDDI node, UDDI Registries in Google Directory, enthusiast sites like XMethods.net.
21. What tags do you need to add within the asp:datagrid tags to bind columns manually? Column tag and an ASP:databound tag.
22. How is a property designated as read-only? In VB.NET:

Public ReadOnly Property PropertyName As ReturnType

  Get             ‘Your Property Implementation goes in here

  End Get

End Property

in C#

public returntype PropertyName

{

   get{

           //property implementation goes here

   }

   // Do not write the set implementation

}

23. Which control would you use if you needed to make sure the values in two different controls matched? Use the CompareValidator control to compare the values
    of 2 different controls.
24. True or False: To test a Web service you must create a windows application or Web application to consume this service? False.

How many classes can a single .NET DLL contain? Unlimited