In cPanel a Alias Domain is a domain that redirects to another location and does NOT have a unique document root.
To use a Alias Domain you need to login to your cPanel account.
Find the “Domains” section in cPanel and click on Aliases (See pic below).
You are now presented with the Alias Domains add panel (See pic below).
Fill in the domain you would like to add. Do NOT include ‘www’.
Click on the Add Domain button.
A list of Alias Domains (if any exist) will be listed at the bottom of the Alias Domains screen. You can see the domain, domain root and if it redirects. Under the Actions area, you can manage the redirection and remove the Alias Domain completely.