Redirect one domain to another on an Apache Web Server

The most straigtforward way to redirect traffic for a domain (or subdomain) you longer wish to use to you new, shiny domain (or subdomain) is the following, simple VirtualHost file:

<VirtualHost *:80>
    ServerName xyz.example.com
    RedirectPermanent / http://abc.example.com/
</VirtualHost>

All traffic to xyz.example.com will now be redirected to http://abc.example.com/. This is also true for whatever query string is added to the domain. E.g. http://xyz.example.com/test will redirect to http://abc.example.com/test.

If you have SSL setup, you might want to add the following VirtualHost file using port 443:

<VirtualHost *:443>
    ServerName xyz.example.com
    RedirectPermanent / https://abc.example.com/
</VirtualHost>

If you wish to redirect multiple subdomains of the same domain to the same, new domain, simply add a ServerAlias:

<VirtualHost *:80>
    ServerName xyz.example.com
    ServerAlias zyx.example.com
    RedirectPermanent / http://abc.example.com/
</VirtualHost>