Configure valid forward and reverse DNS mapping for the computer systems in your domain.
For example OpenSSO Enterprise and the Kerberos Domain Controller must have proper A (IP-Name lookup) and PTR (Reverse IP-Address lookup) records in the DNS database.
If you use the /etc/hosts file instead of using DNS, all host names point to real, network-accessible IP addresses.
For example, if the IP address for host1.example.org is 126.96.36.199, then the /etc/hosts file should contain the following entries:
127.0.0.1 localhost openSSOhost 188.8.131.52 openSSOhost.example.com openSSOhost