How to setup a 301 Redirect

How to setup a 301 RedirectThe “301 Permanent
Redirect” is the most efficient and search engine friendly method for
redirecting websites. You can use it in several situations, including:

• to redirect an old website to a new address
  
• to setup several domains pointing to one website
  
• to enforce only one version of your website (www. or no-www)
  
• to harmonize a URL structure change
  

There are several ways to setup a 301 Redirect, below I will cover the most used ones:
PHP Single Page Redirect
In order to redirect a static page to a new address simply enter the code below inside the index.php file.
<?php
header("HTTP/1.1 301 Moved Permanently");
header("Location: http://www.newdomain.com/page.html");
exit();
?>
PHP Canonical Redirect
The Canonical 301 Redirect will add (or remove) the www. prefixes to
all the pages inside your domain. The code below redirects the visitors
of the http://domain.com version to http://www.domain.com.
<?php
if (substr($_SERVER['HTTP_HOST'],0,3) != 'www') {
header('HTTP/1.1 301 Moved Permanently');
header('Location: http://www.'.$_SERVER['HTTP_HOST']
.$_SERVER['REQUEST_URI']);
}
?>
Apache .htaccess Singe Page Redirect
In order to use this method you will need to create a file named
.htaccess (not supported by Windows-based hosting) and place it on the
root directory of your website, then just add the code below to the
file.
Redirect 301 /old/oldpage.htm /new/http://www.domain.com/newpage.htm
Apache .htaccess Canonical Redirect
Follow the same steps as before but insert the code below instead (it
will redirect all the visitors accessing http://domain.com to
http://www.domain.com)
Options +FollowSymlinks
RewriteEngine on
rewritecond %{http_host} ^domain.com [nc]
rewriterule ^(.*)$ http://www.domain.com/$1 [r=301,nc]
ASP Single Page Redirect
This redirect method is used with the Active Server Pages platform.
<%
Response.Status="301 Moved Permanently"
Response.AddHeader='Location','http://www.new-url.com/'
%>
ASP Canonical Redirect

The Canonical Redirect with ASP must be located in a script that is
executed in every page on the server before the page content starts.
<%
If InStr(Request.ServerVariables("SERVER_NAME"),"www") = 0 Then
Response.Status="301 Moved Permanently"
Response.AddHeader "Location","http://www."
& Request.ServerVariables("HTTP_HOST")
& Request.ServerVariables("SCRIPT_NAME")
End if
%>