The process of adding an addon domain involves the creation of the corresponding subdomain. In terms of Apache VirtualHost entries, an addon is a parked domain on that subdomain.

There is no way to add an addon without a subdomain being created, this is the fundamental principle of cPanel architecture. Nevertheless, it is a common desire to make the links - addon.maindomain.com and maindomain.com/addon unavailable.

There are two ways to achieve this:

1. Redirect both links to a Not Found page using .htaccess which is to be placed into the addon domain web root directory:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{HTTP_HOST} addon.maindomain.com$
RewriteRule ^(.*)$ "http://maindomain.com/404" [R=301,L]
</IfModule>