Hostname and subdomain
What is a Host Name?
A hostname will name a service associated to a domain. The most common hostname is "www" that names the web service for a domain.
What is a subdomain name?
A Subdomain is a domain beneath an existing domain and has it’s own name server referance. Under a subdomain you name multiple hostnames for the service associated to the subdomain.
Example of subdomains:
information.exampledomain.com
wap.exampledomain.com
yourname.exampledomain.com
How do I add a subdomain?
First you must change to Advanced Mode and after click on Domain Admin - Advanced Administration under Domain in the menu on the left-hand side:

click on the edit icon to the right:

Please enter the new IP address or record and then click update: