Follow these guidelines when deciding
on a host name:
Host names can contain from 2 to 63 alphanumeric uppercase
or lowercase characters (a-z, A-Z, 0-9). Fully
qualified host names (for example, mysys.example.com) can contain a maximum of 254 characters. Each component of the
domain name can contain up to 63 characters, and components must be
separated by periods.
Host names must begin with a letter.
Hyphens (-) are permitted in host
names.
Underscores (_) are not permitted
in host names.
Periods (.) are permitted in fully
qualified domain names.
Before deciding upon a host name, consult with your
site administrator to make sure you select a unique name that adheres
to your corporate host naming conventions.