We use OpenDNS as our forwarders here for a few reasons. One they are much faster at what they do than our ISP. Two they don’t drop requests for resolution like our ISP does. Three it is much faster than using Root Hints to resolve and cache manually. Four by combining resolution requests from around the country (globe soon) we can all get better resolution.
Setting this up for an Active Directory enterprise is easy. For each of your DNS servers of which you should have at least two, open up the DNS Management Console, right click on the server and choose Properties. Go to the Forwarders tab and check the box for “Enable Forwarders”. Now add in two IP address for the OpenDNS servers. The IP addresses that you want are 22.214.171.124 and 126.96.36.199. Now whenever your server has a resolution request that it cannot fulfill it will look to the OpenDNS servers instead of using root hints to resolve the query.