How do I set up a Domain Alias with cPanel?

cPanel has an easy option to set up Domain Aliases, which assigns the primary domain of your cPanel an Alias domain.
Look for the "Aliases" option under the Domains panel:
cPanel Domain Aliases
Important: If you're mapping multiple subdomains, check the article about Mapping with Subdomains.
Then, create a new Alias by typing in your Domain:
Create a New Alias
Ensure the document root is the same as your primary WordPress installation.
Domain Root in cPanel
Here's a video about how to configure Aliases in cPanel:
Configuring Addon Domains, Subdomains, and Aliases
Important: When creating the Alias, ensure that the root folder is the same as your Wordpress installation. Additionally, in some server environments "Aliases" may go by a different name and may require a different type of configuration. Other names include Domain Alias, Domain Mapping, Multi-domain, Virtual Hosting, etc. The point is to ensure that the domain uses the same root folder as your WordPress install.
You're now ready to use Domain Mapping System and start mapping domains!