Designing a DNS Services Implementation

A DNS design might include a mixture of the four types of zone database files. You should use Active Directory integrated zones wherever possible; in other words, wherever there are domain controllers. Primary and secondary zones will always have some zone transfer. This should be taken into consideration when designing a DNS infrastructure. Remember that secondary zones are used for load balancing and not for fault tolerance. They should therefore be located near the users who are configured to use them.

If a large company has a small remote office with very few users, it might be advantageous to use a caching-only server. To create a caching-only server, first install DNS on a server without creating any zones, and then configure forwarders for the server. Because the server is not authoritative for a zone, no zone transfer takes place. All queries are resolved from the server's cache or from the forwarders that are configured. A caching-only server thereby saves bandwidth because there is no zone transfer at all. As a caching-only server learns the patterns of its users, it forwards less and less traffic as well.