L2bravo

I am running Windows SBS 2003, and I am using Sharpoint, and when I setup this server I noticed a few things happend. My clients used to be able to go to our website using our .com address now they have to use the .net address, along with our Server using a internal DNS ip address which our clients can view our Intranet site, but when I take out the DNS ip address from there computers, they can not see the Intranet site from there pc’s. so I have to make sure they have the DNS ip address so they can view our company web site and connect to Exchange, I must have configured our server incorrectly, any have any ideas what i might need to do to fix this problem.

Thanks