Why is addon domain connected to subdomain?

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 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>

Make sure to update addon and main domain names correspondingly.

2. Point subdomains addon.maindomain.com and www.addon.maindomain.com to a non-working IP address, e.g. 1.1.1.1, in cPanel – Advanced DNS zone editor menu