Basic Linux webserver - setup without a real domain
I'm new to this server things, so I wonder about the following. I set up a server according to the tutorial here on Howtoforge - "The Perfect Server - OpenSUSE 12.2 x86_64 (nginx, Dovecot, ISPConfig 3)". I plan to use the server as a shared host, for multiple domains. In the tutorial I come to the point, where I have to set up the domain of the server. I wonder, do I have to have a real domain name for the server itself? If the server has a static IP, and I set up the DNS records for the domains that I want to host so that they point to the IP of my server, won't that work? In my opinion i would need to set up the domain only if I hosted also a nameserver for the domains of the server. Do I miss something? I just don't see where do server domain would come to use, except for NS.