1.What is the difference between .NET Framework and .NET Compact Framework ?
The .Net is a Subset of the Full .Net Framework. It implements approximately 30 % of the full .NET Framework class library.
The Main differences are

• The .NET Compact Framework is primarily a rich client platform and does not provide ASP.Net support.
• Both Framework uses assemblies and also access PE files But Compact Framework does not support multi-module. It supports only satellite assemblies.
• The CLR of .NET Compact Framework is only 12 % of the .NET Framework CLR.
• In .NET Compact Framework , the System.Data.OleDb namespace is not supported.
• The .NET Compact Framework does not support the Midpoint Rounding enumeration. In division ,if divisor is very large or very low then the calculation returns zero instead of correct calculation.
• The .NET Compact Framework does not support the .NET Framework Command-Line Debugger (MDbg.exe) which is present in .NET Framework 2.0.
• The .NET Compact Framework does not support config files for tracing.
• The .NET Compact Framework does not support the Activated and Deactivated events.
• The .NET Compact Framework provides exception error message in a seprate DLL, which is System.SR.DLL.
• The .NET Compact Framework uses VB.NET and C# but does not currentely support C++.
• The .NET Compact Framework is optimized for battery-powered systems and avoids heavy use of RAM and CPU cycles.
• The .NET Compact Framework does not support remoting.
• The .NET Compact Framework does not support XML schema validation but supports XML Document Object Model (DOM).

2-What are the different parts of version in an assembly in .NET?
The Version of an Assembly has four parts .
Major The major release number. Incremented when extensive new features or breaking changes are added.
Minor The minor release number. Incremented when minor changes are added and existing features are improved.
Framework Always refers to the target .NET Framework version. 3300 for .NET 1.0, 5000 for .NET 1.1, 0000 for .NET 2.0 Beta 2.
Release 0 for the assembly version. The file version is incremented each time the assembly is released.
The structure of Assembly is
Major.Minor.Framework.Release

3- What is the difference between menifest and metadata ?
Assembly menifest describes about the assembly itself like assembly name, version number, culture information, strong name, type reference etc while the metadata describes about the contents within the assembly like classes, interfaces, namespaces, scope, properties and their parameters etc. The assembly menifest contains the assembly's metadata.

4-Why strings are called Immutable data types ?
Immutability of string means , you can't change the value of that string. If you have to change the value of that string then you have to re-instantiate it.
For example
string str= "Example of string";
str="second example";
Here in the first line I have created a string str and assign a value to it. But what is happening in second line ,first the instance is destroyed and a new instance is created with same name. Unlike other intrinsic data types ,string is a reference type. So in the example the name of the variable remains same but points to a new and different instance of string class which holds a new value

5. What is boxing and unboxing ?
You know about Value types and Reference types. Value types are stored on the stack whereas reference types are stored on the heap.
So the conversion of value types to reference types is known as boxing and converting reference type back to value type is known as unboxing.

6. How do you run Garbage collection in .Net ?
System.GC.Collect( );

7. What is the property available to check if the Page is posted or not ?
The propery to check if the Page is posted or not is "IsPostBack". If it returns a true value then Page is Posted else Page is not posted.

8. What is tracing? What is Page level and application level tracing ?
Tracing provides diagnostic information about a request for an Asp.Net page. The Trace object is an intrinsic object, similer to Request,Response,Server,etc. It is accessible directly with our page code.
We can enable Tracing for page-level as well as application level. After enabling tracing, diagnostic information and custom tracing messages are appended to the output of the page and sent to the requesting browser.
Page-level tracing is enabled by providing "trace=true" in the page directive. This will provide trace information only for that perticular page where tracing is enabled.
Application level tracing is enabled by setting
trace enabled="true" in web.config file.
This will enable the tracing for entire application. Here you don't need to write "trace="true" in page directive.To see the application level trace information, there is a special page called "trace.axd"

9. How many classes can a single .Net DLL contain ?
A single .NET DLL can contain unlimited classes.

10. What is the difference between OleDb Provider and SqlClient ?
SqlClient classes are highly optimizes for .net / SqlServer combination and achieve optimal results. It is also faster than any other Data provider becouse of it's access to the native library.

11. What is the difference between view state and hidden files ?

• Hidden Files contain information that is not visible on the page but is posted to the server along with a page post back While View State is the mechanism that asp.net uses to maintain the state of controls across page post backs. Just like hidden fields and cookies ,view state can be used to maintain state for non control values in a page.
• Hidden Files are used for pages that post to themselves or to other pages while View State works only when a page posts back to itself.
• Hidden Files does not support for storing structured values while View State support for structured values.
  

12. What are the disadvantages of cookies ?
Cookies are used to store small amount of frequently changed information on the client. This information is sent with the request to the server.

• User can disable their browser's ability to receive cookies so it limits it's functionality.
• There is a limitation on the size of cookie.Most of the browsers place a 4096 byte limit on the size of a cookie, although newer browsers are supporting 8192 byte cookie.
• Because cookies are stored at the client, they might be tampered with. Users can manipulate cookies on their computer which can cause a security risk or cause the application that is dependent on the cookie to fail.
• When you request that the browser persist a cookie on a user's computer for a specific period, the browser might override that request by using it's own rules for cookie expiration.
  

13. Why we use Session.abadon( ) Event ?
It cancels the current session .

14. What is the difference between ExecuteReader( ) and ExecuteScaler( ) method ?
ExecuteReader( ) method executes a SqlCommand object and places the result in a SqlDataReader object While ExecuteScaler( ) method Executes a SqlCommand object and returns the first column of the first row of the resultset.

15. How Much Data can we store in a QuerySring ?
Most browser supports for 4096 bytes of data, although newer browsers are supporting 8192 bytes of data.

16. Define Web.config File ?
Web.Config file is a configuration file for asp.net web applications. This file is written in XML format and can contain application-wide data such as database connection string, culture settings etc. It provides a mechanism for Authentication,Authorization and tracing. You can define roles settings in it. The root element of Web.Config file should always be configuration.

17. What is Caching ?
Caching refers to storing information for later retrieval, rather than generating it from scratch every time it's requested. Asp.Net implements three types of caching:
(1) Output caching ( 2 ) Fragment caching ( 3 ) Data caching .
4.18 What is the differnce between Session and Application ?

• In case of application a single application object is shared by all pages and available to all sessions of that application.
• Application is static but session is Dynamic.
• Session have the time out property in which we specify it's Expiration time while application expires when (1) the last session get's closed ( 2 ) Server get's down.
  

19. Can one application supports more than one Web.config file ?
Yes

20. What is the difference Between Structure and Class ?

• Structure is a Value type and stored in stack while Class is a reference type and stored in heap.
• Structures do not support inheritance while Classes do.
• By default all members of structure are public, But in case of class, all constants and variables are private while other members of the class are public by default.
• Sturucture members can't be declared Protected while class members can be.
• A structure must have atleast one nonshared variable while a class can be fully empty.
• A structure does not need a constructure while a class does require it.
• Finalize method is never called for structures as they are never terminated while classes are terminated by GC( Garbage collector ) that calls the Finalize method.

• Even after assigning the value Nothing to a structure variable, instance continues to be associated with the variable and we can access it's data members while in class ,if we assing Nothing to object variable we cannot access any member through the variable untlil you assign another instance to it.

21. What is an ImageMap control ?
ImageMap Web Server control provides individual regions (called hot-spots) on an image which are used for navigation and perform postback event. The Image can be of any standard Web graphic format.
This image contains as many hotspots as required. Each hot-spot is a different element where we can define it's shape. It can be a rectangle, a circle or any polygon.