JSI Tip 6451. Dcpromo may fail with error 123 when the site name is numeric?

If the site name contains only numeric characters, Dcpromo may fail. The %SystemRoot%DebugDcpromo.log contains:

03/19 07:05:22 [INFO] Validating user supplied options
03/19 07:05:22 [INFO] Error - An unknown error occurred while installing the Directory Service. (123)

Error 123 means 'The filename, directory name, or volume label syntax is incorrect'.

You must NOT use numeric site names. You can locate the site name in the log:

'03/19 07:04:06 [INFO] Using site 202002 for server Abc.def'.

NOTE: A valid DNS label must contain at least one non-numeric character, so it can be distinguished from an IP address.