It’s not required, but it is a long standing convention with the justification that it makes for easier troubleshooting.
https://web.mit.edu/kerberos/www/krb5-latest/doc/admin/realm...
It’s not required, but it is a long standing convention with the justification that it makes for easier troubleshooting.
https://web.mit.edu/kerberos/www/krb5-latest/doc/admin/realm...
That's the realm side which should be upper case. The comment reference was for hostname themselves which I've always just done as lower case and have never seen a reason to make it upper case. The krb5.conf has a [domain_realm] section which can map a DNS name/suffix to the actual realm
iirc, on the windows side, workgroups had to be upper case, so initially the krb realm was set to the workgroup name. dns came later