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Using stub zones

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Using stub zones

Use stub zones to:

  • Keep delegated zone information current. By updating a stub zone for one of its child zones regularly, the DNS server hosting both the parent zone and the stub zone will maintain a current list of authoritative DNS servers for the child zone.

  • Improve name resolution. Stub zones enable a DNS server to perform recursion using the stub zone's list of name servers without needing to query the Internet or internal root server for the DNS namespace.

  • Simplify DNS administration. By using stub zones throughout your DNS infrastructure, you can distribute a list of the authoritative DNS servers for a zone without using secondary zones. However, stub zones do not serve the same purpose as secondary zones and are not an alternative when considering redundancy and load sharing.

There are two lists of DNS servers involved in the loading and maintenance of a stub zone:

  • The list of master servers from which the DNS server loads and updates a stub zone. A master server may be a primary or secondary DNS server for the zone. In both cases, it will have a complete list of the DNS servers for the zone.

  • The list of the authoritative DNS servers for a zone. This list is contained in the stub zone using name server (NS) resource records.

When a DNS server loads a stub zone, such as widgets.example.com, it queries the master servers, which can be in different locations, for the necessary resource records of the authoritative servers for the zone widgets.example.com. The list of master servers may contain a single server or multiple servers and can be changed anytime. For more information, see Configure a stub zone for local master servers.

Stub zone updates

Stub zone updates involve the following conditions:

  • When a DNS server loads a stub zone, it queries the zone's master server for the SOA resource record, NS resource records at the zone's root, and glue A resource records.

  • During updates to the stub zone, the master server is queried by the DNS server hosting the stub zone for the same resource record types requested during the loading of the stub zone.

  • The Refresh interval of the SOA resource record determines when the DNS server hosting the stub zone will attempt a zone transfer (update).

  • If an update fails, the Retry interval of the SOA resource record determines when the update is retried.

  • Once the Retry interval has expired without a successful update, the expiration time as specified in the Expires field of the SOA resource record determines when the DNS server stops using the stub zone data.

Use the DNS console in Microsoft Management Console (MMC) to perform the following stub zone update operations:

  • Reload. Reload the stub zone from the local storage of the DNS server hosting the stub zone.

  • Transfer from master. Have the DNS server hosting the stub zone determine if the serial number in the stub zone's SOA resource record has expired, and then perform a zone transfer from the stub zone's master server.

  • Reload from master. Perform a zone transfer from the stub zone's master server regardless of the serial number in the stub zone's SOA resource record.

For more information, see Reload or transfer a stub zone, Add a stub zone, and Understanding stub zones.