Aruba Networks PowerConnect W Clearpass 100 Software Deployment Manual page 355

If you have not already set a unique hostname for this server, you can do so here. Each node in the cluster
must have a unique hostname. A valid hostname is a domain name that contains two or more components
separated by a period (.). Hostname parameters are as follows:
Each component of the hostname must not exceed 63 characters

The total length of the hostname must not exceed 255 characters

Only letters, numbers, and the hyphen (-) and period (.) characters are allowed

Hostnames may start with numbers, and may contain only numbers

Amigopod 3.7 | Deployment Guide High Availability Services | 355