The DNS forwarder in Server 2012 forwards DNS querys that are not resolved locally to an external DNS server.
This video shows you how to setup the DNS forwarder on Server 2012. This will also work on:
*Server 2012 R2
*Server 2008 R2
Open DNS Manager.
In the console tree, click the applicable DNS server.
Then right click the server name and select properties
On the Forwarders tab, under DNS domain, click a domain name.
Under Selected domain’s forwarder IP address list, type the IP address of a forwarder, and then click Add.