Server.Transfer Vs. Response.Redirect

Response.Redirect simply sends a message (HTTP 302) down to the browser.

Server.Transfer happens without the browser knowing anything, the browser request a page, but the server returns the content of another.

To be Short: Response.Redirect simply tells the browser to visit another page. Server.Transfer helps reduce server requests, keeps the URL the same and, with a little bug-bashing, allows you to transfer the query string and form variables.

Something I found and agree with (source):

Server.Transfer is similar in that it sends the user to another page with a statement such as Server.Transfer("WebForm2.aspx"). However, the statement has a number of distinct advantages and disadvantages.

Firstly, transferring to another page using Server.Transfer conserves server resources. Instead of telling the browser to redirect, it simply changes the "focus" on the Web server and transfers the request. This means you don't get quite as many HTTP requests coming through, which therefore eases the pressure on your Web server and makes your applications run faster.

But watch out: because the "transfer" process can work on only those sites running on the server; you can't use Server.Transfer to send the user to an external site. Only Response.Redirect can do that.

Secondly, Server.Transfer maintains the original URL in the browser. This can really help streamline data entry techniques, although it may make for confusion when debugging.

That's not all: The Server.Transfer method also has a second parameter—"preserveForm". If you set this to True, using a statement such as Server.Transfer("WebForm2.aspx", True), the existing query string and any form variables will still be available to the page you are transferring to.

For example, if your WebForm1.aspx has a TextBox control called TextBox1 and you transferred to WebForm2.aspx with the preserveForm parameter set to True, you'd be able to retrieve the value of the original page TextBox control by referencing Request.Form("TextBox1").

Response.Redirect() should be used when:

• we want to redirect the request to some plain HTML pages on our server or to some other web server
• we don't care about causing additional roundtrips to the server on each request
• we do not need to preserve Query String and Form Variables from the original request
• we want our users to be able to see the new redirected URL where he is redirected in his browser (and be able to bookmark it if its necessary)

Server.Transfer() should be used when:

• we want to transfer current page request to another .aspx page on the same server
• we want to preserve server resources and avoid the unnecessary roundtrips to the server
• we want to preserve Query String and Form Variables (optionally)
• we don't need to show the real URL where we redirected the request in the users Web Browser

Response.Redirect() will send you to a new page, update the address bar and add it to the Browser History. On your browser you can click back.

Server.Transfer() does not change the address bar. You cannot hit back.

I use Server.Transfer() when I don't want the user to see where I am going. Sometimes on a "loading" type page.

Otherwise I'll always use Response.Redirect().