Once the host is in Maintenance mode, you need to disconnect (right click on host name, and select disconnect) from the cluster.

Then you can directly connect with VIC to that host. Putty to the host, edit the /etc/hosts and /etc/sysconfig/network files and change the appropriate host name. Save the files, reboot the host, verify the host name is correct.

Be sure to update your DNS/DHCP entries with the new host name on your network, and then you can remove the host from your cluster, and then right click on the cluster, add the host by it's new name, and that's it.

You should be complete after that.

The only thing he wants is to make it easier to identify BY IP the machines in his cluster, for him IP address is easier to identify the host. But the IP address showing in the console won't affect the overall scheme of things communicating. It's just a visible appeal. That's why there are agents on each of the ESX hosts.. they don't rely on the console to talk to each other, the console is JUST for monitoring the servers in one place, because that's why you can close your session in VC, and the operations will still work....