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Managing a Forward Lookup Zone

Applies To: Windows Server 2008

As you divide your Domain Name System (DNS) namespace into domains, you also divide your DNS namespace into one or more zones, each of which stores name information about one or more DNS domains. A zone is the authoritative source for information about each DNS domain name that is included in the zone. A forward lookup zone is the most common type of zone. DNS clients can use this zone to obtain such information as IP addresses that correspond to DNS domain names or services that is stored in the zone. Another type of zone, a reverse lookup zone, provides mapping from IP addresses back to DNS domain names. For more information about reverse lookup zones, see Providing Reverse Lookup.

A zone starts with a single DNS domain name. If other domains are added below the initial domain, these domains can either be part of the same zone or belong to another zone. That is, when you add a subdomain, you can either include it as part of the original zone, or you can delegate it away to another zone that you create to support the subdomain.

A stub zone is a special type of forward lookup zone that contains information only about the authoritative name servers for the zone. The zone at this server must be obtained from another DNS server that hosts the zone. This DNS server must have network access to the remote DNS server to copy the authoritative name server information about the zone. Stub zones are useful for keeping delegated zone information current, improving name resolution by avoiding queries to root servers, and simplifying DNS administration by reducing the need for secondary zones.

Because of the important role that zones play in DNS, they must be available from more than one DNS server on the network so that they can provide availability and fault tolerance. Otherwise, if only a single server is available and that server is not responding, queries for names in the zone can fail. So that additional servers can host a zone, zone transfers are required for replication and synchronization of all the copies of the zone that are used at each server that is configured to host the zone.


Zones that are integrated with Active Directory Domain Services (AD DS) use directory replication to transfer zone data between DNS servers. Zones that are not integrated with AD DS (that is, that store zone data in files) use conventional zone transfer to propagate zone changes among primary and secondary DNS servers.

Zones that are integrated with AD DS usually require little or no management apart from the management of the corresponding AD DS forests and domains. Most of the following tasks are required only for a zone that is not integrated with AD DS.

This section includes the following tasks for administering DNS: