domain name system - How do I access the internet without setting all clients to static IP's? Server 2012

I have a small business network using a server that runs Windows Server 2012. It is currently configured with the following roles: ADDS, HDCP, and DNS. The hierarchy is simple: A gateway/firewall, with DHCP services turned off (obviously, since there is a DHCP server), which has the DNS servers IP to direct all clients requesting IP's from the DHCP server within the domain. Also, the server is set in the DMZ within the gateway. With DNS, I have the local domain, for intranet name resolution, and then outside DNS IP's to resolve internet names. The DHCP server has the IP ranges set, and the DHCP server has been authorized, as well as the IP ranges activated. All of the client computers are running Windows 7, and are on the domain. The DHCP server has been able to issue out the IP's to the clients, that are all set to 'obtain IP and DNS addresses automatically'. For some reason, even though the server itself has internet access, none of the clients can access the internet, unless I issue each one of them static IP's, and static DNS. THis is really simple stuff, but for some reason I cannot for the life of me figure this out. Hopefully I did not omit anything pertinent to this situation.