This will tell you how to do it. It talks a little more about using the virtual domain function. But you can apply the same function to the primary domain set up also. If you have any questions just write me back and I can clear it up.

First off I do not use my ISP’s DNS for anything it just causes problems.. I leave my server free of DNS info it does it’s own DNS lookups. ISP’s fiddle with their DNS servers too darn much.
Anyway I purchase my domain names from 000domains.com, after that I go to
www.zoneedit.com to set up my free DNS account to host my domain name.. I add the name to my DNS account and point the names to my static IP 4 ways :
www.mydomain.com, mail.mydomain.com, mydomain.com and ftp.mydomain.com . Then I go back to 000domains.com and use the DNS servers that zoneedit gives you as the primary and secondary DNS servers for your domain name.
After that I make a new user group on my e-smith server to hold the accounts for the users that need to access the new domain. Then I make a new Ibay and give access to the new Ibay to that new group. Then I make whatever new users I need to make for e-mail purposes etc.
Then I add my domain to the virtual domain area and point it to the new Ibay I made and that is it..
So far the only problem I have had is that using anything other then
www.mydomain.com will point to the primary website but
www.mydomain.com points to the Ibay I have set up! I don’t know why that happens and it does not always happen.
But I hope this is of some help.. Oh and 000domains.com is cool cause they are fast and you control your account through their web interface and never have to deal with the company unless you have a problem. And zoneedit is the same all web administer and you can host 5 domains for free plus set up web and e-mail forwarding, web parking etc.