Ensure that the computer name comprises a unique network name of 15 characters or less. It can possibly contain alphanumeric characters and hyphens (-) and must begin with an alphabetical character. Make sure that the computer name and workgroup labels follow the rules for ARPANET host names.
Note: Although Microsoft allows the use of the underscore character (_) as part of the naming convention, Cisco strongly recommends that you do not use the underscore character in the hostname for this computer. Use of the underscore character can result in lost session variables and cause certain windows and features not to work.
The format for Domain Name System (DNS) domain names comprises labels that are separated by single dots. Each label consists of 1 to 63 characters with a maximum of 255 characters, that includes the separating dots, for the entire domain name.
Labels must adhere to these naming conventions:
Ensure that computer name starts with a letter.
Ensure that the computer name ends with a letter or digit.
Ensure that the interior characters of the computer name contain only letters, digits, and hyphens.
Ensure the computer name is unique to your network.
Ensure the computer name is not longer than 15 characters.
Do not include a space anywhere in the computer name, which includes spaces that lead or trail. Do not use these characters and symbols, which are not valid entries in computer names: \ " / [ ] : | < > + = ; , ?.
Note: When you enter a DNS name that includes UTF-8 or underscore character that is not listed in RFC 1123 while you modify the host name, DNS suffix, or create an Active Directory domain on the DNS server that is provided with this server, a message displays to warn that some DNS server implementations can possibly not support these characters.
Caution: Failure to adhere to the described naming convention results in an inoperable Cisco CallManager system and a complete loss of configuration information and data on a Cisco CallManager publisher server.
Caution: The host name (computer name) for a Cisco CallManager server cannot start with a digit. When you choose a host name that begins with a digit, a Cisco CallManager server does not function properly.
Note: If you change the computer name after the application installation, you must reinstall the operating system and the application.