WordPress 3.1 Multisite installation guide with domain mapping

WordPress 3.1 Multisite installation guide. Here I’ll walk though the simple steps to enabling multisite within your existing wordpress installation and then allowing domain mapping you can host multiple domain from within one wordpress installation. Domain mapping isn’t the same as sub folders or sub directories, domain mapping allows you to host multiple fully qualified domain name from one wordpress 3.1 installation.

Step 1: Install WordPress 3.1 as normal

Step 2: edit wp-config.php and add (just above the debug line)

define(‘WP_ALLOW_MULTISITE’, true);

Step 3: From within the WordPress Admin Panel click – Tools – Network –  Select sub-domain

You now have wordpress 3.1 multisite enabled –

Now let’s move on to Domain mapping !

Domain mapping allows you to host multiple domains within your wordpress multisite (wpmu) installation. So you don’t have to deal with subfolders and sub domains!

You’ll need to simply install the domain mapping plugin http://wordpress.org/extend/plugins/wordpress-mu-domain-mapping/

1. Install the plugin in the usual way into the regular WordPress plugins folder. Network activate the plugin. After activation you’ll see a screen telling you to make changes to wp-config.php and .htaccess – do that! duh!
2. Move sunrise.php into wp-content/. If there is a sunrise.php there already, you’ll just have to merge them as best you can.
3. Edit wp-config.php and uncomment or add the SUNRISE definition line. If it does not exist please ensure it’s on the line above the last “require_once” command. define( ‘SUNRISE’, ‘on’ );
4. As a “super admin”, visit Super Admin->Domain Mapping to create the domain mapping database table and set the server IP address or a domain to point CNAME records at.
5. Make sure the default Apache virtual host points at your WordPress MU site or WordPress 3.0 network so it will handle unknown domains correctly. On some hosts you may be required to get a dedicated IP address. A quick check: in a web broswer, type in the IP address of your install. If you are using CPanel, use the Park a Domain menu to set the mapped domain to your main installtion.
6. Do not define COOKIE_DOMAIN in your wp-config.php as it conflicts with logins on your mapped domains.

Couple more changes and you’re done –

Under Super Admin->Domain Mapping – you need to only select

• Permanent redirect (better for your blogger’s pagerank)
• User domain mapping page

Server IP Address: x.x.x.x – make sure you have your virtual host set to look to this IP. Also each virtual host will use the document root set for your main wordpress install.

Comment below if you need help with your installation. Comments are held for moderation so check back tomorrow for my reply.