Windows 2000 DNS

Zone Transfer Considerations

Windows 2000 supports a method of zone transfer called fast zone transfer. With fast zone transfer, the Windows 2000 DNS server can send more than one resource record per message. This is more efficient than sending only one. However, some third-party DNS servers, including servers that are running versions of BIND earlier than 4.9.5 do not support fast zone transfer. If you use a secondary server that does not support fast zone transfer, disable fast zone transfers on the master server by selecting the check box Bind secondaries on the Advanced tab of the properties for your server, from within the DNS console.

Many DNS servers, including servers that are running versions of BIND earlier than 8.2, do not support incremental zone transfer, another method of zone transfer. With incremental zone transfer, instead of transferring a whole zone, a DNS server can transfer only those portions of the zone that changed since the last time the secondary server queried. However, this does not cause interoperability problems, because Windows 2000 can still use full zone transfer if any of the secondary servers do not support incremental zone transfer.

Windows 2000 also supports resource record types that other servers might not support, such as the WINS record and the WINS-R record. If you have a primary copy of a zone on a Windows 2000 DNS server and a secondary copy of a zone on a third-party DNS server, and the primary zone includes resource records the third-party server does not support, the secondary server might drop those resource records, or it might not be able to transfer the zone. For information about WINS records, see "WINS Considerations" earlier in this chapter.

It is also possible that a third-party DNS server might support a resource record type that Windows 2000 does not support, such as resource records not listed in the RFCs. If you have a primary copy of the zone on a third-party DNS server and a secondary copy on a Windows 2000 server, and the primary zone includes resource records that the Windows 2000 DNS server does not support, the Windows 2000 DNS server drops those resource records. If it receives any circular CNAME records, it drops those as well. You can also configure your DNS server to halt a zone transfer when it receives a resource record it does not support.

For information about problems with zone transfer, see "Diagnosing Name Resolution Problems" later in this chapter.