Windows Server 2008 R2 Domain Controller with Windows 7 Professional Clients (DNS problems)

I have a Microsoft Windows Server 2008 R2 Server as a Domain Controller with three Microsoft Windows 7 Professional clients. Two of the clients are laptops, while the other client is a desktop. In order for a Windows 7 Professional client to connect to my domain controller, I have to go under Control Panel, Network and Internet, Network and Sharing Center, Change adapter settings, Wireless Network Connection (laptops) or Local Area Connection (desktop), Internet Protocol Version 4, and for a preferred DNS server I need to enter the DNS of my domain controller, which is 192.168.1.202. The IP address is static and does not change. The problem is that even though my laptops will connect to the Internet just fine within my network, when I try to connect to a different network with my laptops, I can not access the Internet. I am guessing this is happening because the preferred DNS server does not exist on other networks. Is there a way I can still connect to my domain controller on my network without having to manually change my preferred DNS server when I connect to a different network? Any answers or suggestions would be greatly appreciated, as this situation has become very frustrating.