I've already posted on configuring DHCP + Dynamic DNS for some operating systems.

I still claim that that's the only way to go for dynamic, trusted networks.

So after RedHat, Debian/Ubuntu, Windows, it's about time to stop the IP suffering with Solaris as well:

1. Make sure /etc/nodename contains the FQDN, e.g. "snoopy.ac.uk"
2. touch /etc/dhcp.<interface name> . There are two peculiar parameters I'm not fully sure about their meaning (how come they're not needed in other OSes?) - but here is what I used:
   1. add "primary" (a separate line) if it's the primary interface.
   2. Add "wait <seconds>" (a separate line) - I put "wait 60" to be on the safe side.
3. /etc/hostname.<interface name> should have the hostname inside. NOTE! It's the hostname dhcp client would send (Option 12) to the server for Dynamic DNS registration. According to /etc/defaults/dhcpagent, the format is "inet name", e.g. "inet snoopy"

That should be it, then. Please add your comments and corrections.