I have a RaQ4i and I host many web sites. I also provide them DNS services, using ns1.mydomain.com and ns2.mydomain.com. Now I also have another server which has been set to run DNS as ns3.mydomain.com and ns4.mydomain.com. What do I have to set in the Cobalt RaQ in order the subdomains [ns3.mydomain.com] and [ns4.mydomain.com] to run as name servers to the other server? Just changing the A Rerord for these subdomains? I don't think so..

I think just setting an A record for ns3.mydomain.com and ns4.mydomain.com on your first server to point to the IP of the second server should do.

HOWEVER... if you are running both the ns1 and ns2 from one server (your current server) and that server goes down then your dns entries for ns3 and ns4 are no longer available and after a while the second server can no longer be found by anyone.

And if the ns3 and ns4 can no longer be found because the DNS for it is down (your first server) then all the sites on it that rely on the ns3 and ns4 for nameservers are ALSO down.

* I reserve the right to be wrong

Yes, I know that. I will do this way only for a few days, until I move all the sites to the new server.

register ns3/4 at internic thru your registrar
add ns3 as an additional nameserver for your domain
have your sites' zone records identical on both servers

have a records for all 4 ns