RHEL 7.2: using realm to join AD domain
I encountered same error message trying to join an AD domain on a CentOS 7.2 server. However, contrary to the directions, passing just the username worked for me:
realm join example.edu -v -U 'adm-jsmith'
I tried many things until I saw the answer above just using the user name. That was the key. I kept getting a kerberos failure to find kdc and a kerberos failure to authenticate messages until I used the following:
realm --verbose join -U 'administrator' host.domain.com