Beta Host Limited offers unlimited Addon Domains, for all accounts except for the Basic Plan, Premium, & Business Plan. This article explains what an Addon Domain is and how it can be accessed.
A domain must be assigned to the account before it can be used as an addon domain.
How an Addon Domain Works
An addon domain is a fully functional domain that can be created from within your control panel (cPanel). This addon domain is a new, unique website hosted in a new folder on your account so that you can host several domains from one control panel. You can give an addon domain email addresses, forwarders, and more the same way as a primary (main) domain on the account.
When you create an Addon domain, 3 things happen:
a folder is created in the 'public_html' directory
a subdomain is created for the primary domain and attached to the new folder
the new domain name is associated with the subdomain
For example, if the primary domain was 'abc.com' and you assign the Addon Domain '123.com' to the folder '123', the following routes (URLs) would be true:
All three of these paths would access the same directory and show the same website. However, in concern to your website's viewers going to 123.com , there is no evidence that they are being routed through 123.abc.com and everything will function as normally.
This all happens automatically when an Addon domain is assigned to an account; there is no need further action necessary other than loading content into the addon domain folder.
Additionaly, for those still concerned with 123.abc.com being active, there is a method in which you can disable the 123.abc.com route from accessing the site without disturbing the 123.com route.