If you have created any WordPress MU sites and wanted the ability to Map a Domain to a one of your blogs, the domain mapping plugin will come of great use. There are two different plugins. There is a plugin available from WPMUDEV.org and there is one at the depository called WordPress MU domain mapping. The latter is the one we will go a bit into. I wrote a post regarding the plugin earlier ”
WordPress 101 Guide – Domain mapping on WordPress MU has never been easier!.

If you have tried the plugin and have run into the redirect loop issue there is a solution. The system we are describing had issues from the start. It runs Interworxs and Siteworxs. Domains where originally managed at a different location.

All steps where done. Cname was created on DNS manager to point to subdomain of blog. Domain mapping plugin is set up. The first issue was the site would not appear. To solve this issue when using Siteworxs – make sure to add the domain even though it will create it’s own filesystem.

Once this is created. The Redirect loop appeared. As the domain name was directed to the subdomain and back and forth.

How did we solve it.
First –

Create two pointer domains. One for the domain to be mapped and One for the subdomain. They point to the original blog domain.

Create two Cname records. One for the domain to be mapped, pointing to itself and one for the subdomain doing the same.

Ex. www.mydomain.com CNAME mydomain.com 43200
www.subdomain.mydomain.com CNAME subdomain.mydomain.com 43200

Make sure to copy the sunrise.php file to your Wp-content directory.
Add the following to your wp-config.php file:
define( ‘DOMAIN_CURRENT_SITE’, ”. $_SERVER[‘HTTP_HOST’].” );
define(‘NOBLOGREDIRECT’, ”);

Uncomment – define( ‘SUNRISE’, ‘on’ );

After you have finished the steps, you should have a fully working mapped domain. Repeat the procedure with every mapping you need to create.

With Siteworxs – the procedure is a bit repetitive and cumbersume.