Configure through “Admin/Customer Settings”
Enter one or more domain names, separated by comma.
The domains name will be mapped to the customer’s log in page.
For example, if I own the domain name acme.com and I want to set up http://support.acme.com for my customer service site. Then I can enter support.acme.com into the domain mapping field. And configure domain server to point support.acme.com to ihelpdesk.com