Alternatives to modifying host files

Ok here is my situation. I am trying to access a server within a domain on a client machine out side of the network through a VPN tunnel. The way this thing os set up is everyone in the LAN can access this server (which is hosting our intranet) with no problems. But as soon as you go outside of the network on the WAN or using a VPN from home, the only way you can access the server for its resources is by modifying the host file. Im trying to avoid doing that. Is this a DNS issue? Or what?