I have 3 domain controllers all running Windows 2003 Server R2 with dns installed. I have some users that travel and work from home. Those users have issues resolving our websites because dns is resolving them to the external IP instead of the internal local IP. If they repair their network connection this usually fixes it. Below is a very detailed explanation of the problem I found online but the solution they proposed did not work properly in my environment.
"Another problem is that you are connected to the internet but there is a conflict between the DNS name you are using internally and the same domain name that is registered on the internet. Confusion may be caused by your web server or your Exchange server registering the same domain name but with a different IP address. For instance your ISP or InterNic may have legitimately assigned a different IP address for your domain name."