Here's a small quick FAQ on ASP.NET in Interview. In this section we will cover main types of validation controls which are provided by ASP.NET .
		There are six main types of validation controls:-
		
				RequiredFieldValidator
				
 
		It checks whether the control have any value. It is used when you want the control should not be empty.
		
				RangeValidator
				
				
		
		It checks if the value in validated control is in that specific range. Example TxtCustomerCode should not be more than eight lengths.
		
				CompareValidator
				
				
		
		It checks that the value in controls should match some specific value. Example Textbox TxtPie should be equal to 3.14.
		
				RegularExpressionValidator
				
				
		
		When we want the control, value should match with a specific regular expression.
		
				CustomValidator
				
				
		
		It is used to define User Defined validation.
		
				Validation Summary
				
				
		
		It displays summary of all current validation errors on an ASP.NET page.
Also see the following 
ASP.NET Training and interview questions video: -How to build-up single 
sign-on using ASP.NET forms authentications.
 
		
		
		
Do visit for more
important ASP.NET interview questions and answer atwww.questpond.com
The above question is taken from the
book .NET interview questions published by BPB publication and written by 
Shiv Prasad Koirala.