To configure DNS forwarding:
Click Start, point to Programs, point to Administrative Tools, and then click DNS to start the DNS Management Console. Right click the DNS Server object for your server in the left pane of the console, and click Properties.
Click the Forwarders tab. Check the Enable forwarders check-box.
In the IP address box enter the IP address of the DNS servers you want to forward queries to - typically the DNS server of your ISP. You can also move them up or down. The one that is highest in the list gets the first try, and if it does not respond within a given time limit - the query will be forwarded to the next server in the list.