the first roll is tip ADDS (Active Directory Domain Services) and from that point on your system becomes a true server as different to a local machine... I would assume you don't have your domain set up or that the other computers don't get seen by the server as being in that domain yet.
Both Microsoft DNS and DHCP servers can run without a domain in certain configurations. I would wager that the OP did not bind a NIC at some level on the DHCP server.