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1. Explain the life cycle of an ASP .NET page.?

Following are the events occur during ASP.NET Page Life Cycle:

1)Page_PreInit

2)Page_Init

3)Page_InitComplete

4)Page_PreLoad

5)Page_Load

6)Control Events

7)Page_LoadComplete

8)Page_PreRender

9)SaveViewState

10)Page_Render

11)Page_Unload

Among above events Page_Render is the only event which is raised by page. So we can't write code for this event.

2. how does the cookies work in asp.net?

we know Http is an state-less protocol which is required for interaction between clinet and server .

so there is an need to remeber state of request raised by an web browser so that 

web server can recognize you have already previously visited or not.

There are two types of state management techniques:

a) Client side state management

b) Server - side statemanagement

Using cookies comes under clinet side statemanagement .In HttpResponse we write 

Cookie containing sessionId and other information within it.

when a browser made a request to the web server the same cookie is sent to the server where server recognize the session id and get other information stored to it previously.

3. What is Ispostback method in ASP.Net? Why do we use that??

Basically Post back is an action performed by a interactive Webpage. When it goes to the server side for a non-client Operation Server again posts it back to the client and hence the name.

Ex:

if(!IsPostBack)

will not allow the page to post back again n again bcoz it reduces the performance.

5. what is the difference between application state and caching?

Application Object and Cached Object both falls under Server side State Management.

Application object resides in InProc i.e. on the same server where we hosted our application.

Cache Object resides on server side/ DownStream/Client Side.

Application Object will be disposed once application will stop.

Cache Object can be disposed using Time based cache dependency.

Only one user can access Application Object at a time hence we have to lock it every time we modify it.

6. what is boxing and unboxing?

Boxing is what happens when a value-type object is assigned to a reference-type variable.

Unboxing is what happens when a reference-type variable is assigned to a value-type variable.

7. What are the uses of Reflection??

Reflection is a concept using which we can 

1) Load assemblies dynamically

2) Invoke methods at runtime

3) Retriving type information at runtime.

8. What is the use of AutoWireup in asp.net?

AutoEventWireup attribute is used to set whether the events needs to be automatically generated or not.

In the case where AutoEventWireup attribute is set to false (by default) event handlers are automatically required for Page_Load or Page_Init. However when we set the value of the AutoEventWireup attribute to true the ASP.NET runtime does not require events to specify event handlers like Page_Load or Page_Init.

9. what events will occur when a page is loaded?

Below are the events occures during page load.

1) Page_PreInit

2) Page_Init

3) Page_InitComplete

4) Page_PreLoad

10. Where is the View state Data stored?

ViewState data is stored in the hidden field. When the page is submitted to the server the data is sent to the server in the form of hidden fields for each control. If th viewstate of the control is enable true the value is retained on the post back to the client when the page is post backed.

12. Where do the Cookie State and Session State information be stored?

Cookie Information will be stored in a txt file on client system under a 

folder named Cookies. Search for it in your system you will find it. Coming to Session State

As we know for every process some default space will be allocated by OS.

In case of InProc Session Info will be stored inside the process where our 

application is running.

In case of StateServer Session Info will be stored using ASP.NET State Service.

In case of SQLServer Session info will be stored inside Database. Default DB 

which will be created after running InstallSQLState Script is ASPState.

14. What are the different types of sessions in ASP.Net? Name them.?

Session Management can be achieved in two ways

1)InProc

2)OutProc

OutProc is again two types

1)State Server

2)SQL Server

InProc

Adv.:

1) Faster as session resides in the same process as the application

2) No need to serialize the data DisAdv.:

1) Will degrade the performance of the application if large chunk of data is stored

2) On restart of IIS all the Session info will be lost

State Server

Adv.:

1) Faster then SQL Server session management 

2) Safer then InProc. As IIS restart 

won't effect the session data

DisAdv.:

1) Data need to be serialized

2) On restart of ASP.NET State Service session info will be lost

3)Slower as compared to InProc

SQL Server

Adv.:

1) Reliable and Durable

2) IIS and ASP.NET State Service 

restart won't effect the session data

3) Good place for storing large chunk of data

DisAdv.:

1) Data need to be serialized

2) Slower as compare to InProc and State Server

3)Need to purchase Licensed 

version of SQL Serve

16. What is caching? What are different ways of caching in ASP.NET?

Caching is a technique of persisting the data in memory for immediate access to requesting program calls. This is considered as the best way to enhance the performance of the application.

Caching is of 3 types:

Output Caching - Caches the whole page.

Fragment Caching - Caches a part of the page

Data Caching - Caches the data

17. What is meant by 3-tier architecture.

We generally split our application into 3-Layers

1)Presentation Layer ( Where we keep all web forms Master Pages and User Controls).

2)Business Layer (Where we keep business logic). e.g Code related to manipulating data Custom Exception classes Custom Control classes Login related code if any etc. etc.

3)Data Access Layer (Where we keep code used to interact with DB). e.g. We can have the methods which are using SQL Helper (Application Block).

19. What is the difference between mechine.config and web.config?

machine.config is a system level configuration i.e it is applied on all application in o/s that the configuration is set where as in web.config it is applicable to only one application i.e each asp.net webapplication will contain atleast on web.config file.

21. What is the difference between Response.Redirect and Server.Transfer.

Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client's browser. This provides a faster response with a little less overhead on the server.Server.Transfer does not update the clients url history list or current url. 

Response.Redirect is used toredirect the user's browser to another page or site. This performs a trip back to the client where the client's browser is redirected to the new page. The user's browser history list is updated to reflect the new address.

25. What is the exact purpose of http handlers?

ASP.NET maps HTTP requests to HttpHandlers. Each HttpHandler enables processing of individual HTTP URLs or groups of URL extensions within an application. HttpHandlers have the same functionality as ISAPI extensions with a much simpler programming model

Ex

1.Default HttpHandler for all ASP.NET pages ->ASP.NET Page Handler (*.aspx)

2.Default HttpHandler for all ASP.NET service pages->ASP.NET Service Handler (*.asmx)

An HttpHandler can be either synchronous or asynchronous. A synchronous handler does not return until it finishes processing the HTTP request for which it is called. An asynchronous handler usually launches a process that can be lengthy and returns before that process finishes

After writing and compiling the code to implement an HttpHandler you must register the handler using your application's Web.config file.