[Skunkworks] Windows Domain Controller Question

Good people, I seek thine counsel. I have an intranet server running CentOS 5.5, the hostname of this machine is *intranet*. The users who will be accessing this intranet will be accessing it from Windows XP and 7. The AD and DC are on Windows Server 2008. My sys admin is sceptical that it is possible for a user to type http://intranet/ on their machine and access the app, she says I have to use the IP address. Unfortunately, I have close to zero knowledge of Windows Domain Controllers, therefore, I am at a loss for facts to use to challenge the evil sys admin. Can someone please point me in the right direction?