It is common practice in Web applications to move pages and other content around over time, which can lead to an accumulation of stale links in search engines. In ASP.NET, developers have traditionally handled requests to old URLs by using by using the Response.Redirect method to forward a request to the new URL. However, the Redirect method issues an HTTP 302 Found (temporary redirect) response, which results in an extra HTTP round trip when users attempt to access the old URLs.
ASP.NET 4 adds a new RedirectPermanent helper method that makes it easy to issue HTTP 301 Moved Permanently responses, as in the following example:
RedirectPermanent("/newpath/foroldcontent.aspx");
