I actually had read that before posting. My question is what about ip addresses that have multiple domains attached to them. like web servers that host more than 1 webpage. or in this case email servers that host more than one email domain. a reverse dns with querey IP address 1.2.3.4 but at that ip address it may be hosting 20 domains, so what does the querey return?

I understand how the look up works if its 1 name 1 ip address. but not 1 ip address for 30 names.