|asthelen you are missing a number of key concepts concerning networking and Active Directory.|
Yes the server will be on the lan
Yes you will assign only the domain users you want assigned to the server.
Yes you will deny all other users from this server.
In other words you want this server as a member server of the domain so you CAN control access to it.
This is not a matter of not having it on the lan. You can't do anything with that concept.