Adding a Secondary DNS Server to a Zone

Applies To: Windows Server 2008

Secondary Domain Name System (DNS) servers help provide load balancing and fault tolerance. Secondary DNS servers maintain a read-only copy of zone data that is transferred periodically from the primary DNS server for the zone. You can configure DNS clients to query secondary DNS servers instead of (or in addition to) the primary DNS server for a zone, reducing demand on the primary server and ensuring that DNS queries for the zone will be answered even if the primary server is not available.


Active Directory–integrated zones do not ordinarily employ secondary DNS servers. Active Directory–integrated zones use Active Directory replication instead of zone transfer to synchronize zone data among DNS servers.

Typically, adding a secondary DNS server to a zone involves three steps:

  1. On the primary DNS server, add the prospective secondary DNS server to the list of name servers that are authoritative for the zone.

  2. On the primary DNS server, verify that the transfer settings for the zone permit the zone to be transferred to the prospective secondary DNS server.

  3. On the prospective secondary DNS server, add the zone as a secondary zone.

To complete this task, perform the following procedures:

  1. Specify Other DNS Servers as Authoritative for a Zone

  2. Modify Zone Transfer Settings

  3. Add a Secondary Server for an Existing Zone