Adding and Removing DNS Servers

Applies To: Windows Server 2008

Domain Name System (DNS) servers provide the essential services for name resolution in a TCP/IP-based network. To resolve DNS names properly, a DNS client must be able to access a DNS server that it can query. For this reason, it is often necessary to have multiple DNS servers on a network to provide load balancing and optimal network performance.

In a network in which Active Directory Domain Services (AD DS) is deployed, the DNS Server role is most often installed on domain controllers. This simplifies DNS administration by making it possible for the Active Directory domain namespace and the DNS domain namespace to be maintained simultaneously. In some cases, however, it might be necessary to install the DNS Server role on a stand-alone server (that is, a server that is not a domain controller)—for example, to provide load balancing or to support a network that does not deploy AD DS.

You can install a DNS server as a caching-only server. Although all DNS servers cache queries that they have resolved, caching-only servers only perform queries, cache the answers, and return the results. They are not authoritative for any domains, and the information that they contain is limited to the information that they cache as they resolve queries. These servers obtain this information over time as they process client requests, and so network traffic between caching-only servers and authoritative DNS servers will be highest when the caching-servers are first deployed. However, if you are have a slow-speed wide area network (WAN) link between sites, this option might be ideal because, after the cache is built, traffic decreases. In addition, a caching-only server does not perform zone transfers, which can also be a big user of network resources in WAN environments.

This section includes the following tasks for administering DNS: