This article applies to 123-reg servers running Plesk.
This article will explain how you can change the hostname of your server using Plesk 11.
Login to your Parallels Plesk Panel.
Click on the Server tab.
Click on the Server Settings link under the General Settings section.
Change the Hostname of your server in the Full hostname field.
Click on the OK button to save the change.
Plesk will then automatically update its database and all needed configuration files with the updated hostname.