DNS forwarder

Assuming that the DNS service is started, you would use DNS Manager from the Administrative Tools. Follow the steps below to configure forwarders:

1. In DNS Manager, right-click the DNS Server object, and then click Properties.
2. Click the Forwarders tab.
3. Click to select the Enable Forwarders check box.
4. In the IP address box, type the first DNS server to which you want to forward, and then click Add.
5. Repeat step 4 until you have added all the DNS servers to which you want to forward.
6. Click OK when finished.

If you need to install the DNS service, follow the steps below:

http://support.microsoft.com/default.aspx?scid=kb;en-us;300202&sd=tech

Also make sure there is no 'root' dns domain configured in DNS (indicated by just a '.' (dot)).
If that still exists then it will not use forwarders or root hints.

http://support.microsoft.com/default.aspx?scid=kb;en-us;300202

BFilmFan is correct, except if your server is configured as a root server. It should not be configured as a root server if it is not the authoritative, registered DNS host server for your domain. If your DNS zone is hosted elsewhere, for example, on your ISP's DNS Server, then your internal DNS server should not be configured as a root server for your domain. To find out if this is the problem, open the DNS management console on your server and look at the objects listed in your zone. If there is a folder labeled ".", then you have a root zone configured on your DNS server. You can fix this simply by deleting the "." object; then stop and restart DNS. After this, you should be able to configure forwarders for your DNS server just as described by BFilmFan.

Hope this helps!