In a SharePoint Server 2007 or later or a SharePoint Foundation or WSS installation, a Web application can be redirected within the same farm. The source Web application should not be a live Web application. The target Web application where you want to redirect the restore must already exist on the specified Web server. It must also have the same database structure as the source Web application.
Note the following when you redirect a Web application:
You can only redirect the restore of Web applications and they must be restored at the database level. You can restore Configuration databases and Single Sign-on databases back to the original location only. Document sets and individual SharePoint items must be restored to their original site.
You can redirect a restore of a Web application within the same farm. The SQL database host and the SharePoint host must be the same. A redirected restore is not supported if the SQL databases exist across multiple SQL hosts.
To redirect a restore of a SharePoint Web application