Microsoft windows 2000 DNS manual Dynamic Update

The following diagram details the incremental transfer mechanism.

Zone Log File

Serial Number 12

changes

Serial Number 11

changes

Serial Number 10

changes

Master DNS

Server

Serial Number 12

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Serial Number 11

Serial Number 8

Serial Number 10

Slave DNS

Server 1

Slave DNS

Server 2

Slave DNS

Server 3

IXFR and DS Integration

As was mentioned above, IXFR is an order-based protocol, which will send the zone changes based on differences in the zone serial numbers. In a DS integrated multi-master environment, changes to a DNS zone can be applied to any master server. Therefore, different master servers will contain the zone changes applied in a different order. This can cause problems in situations where a master IXFR server that provided the zone changes to an IXFR client the last time is not available. If the IXFR client selects another master server with zone changes applied in a different order, the integrity of the IXFR client’s zone may be compromised after the incremental transfer. In this case the server initiating a zone transfer will request AXFR.

In summary, the DNS server could be a Slave and a Master with respect to the same zone at the same time. This can happen if the zone is replicated from the Master, server1, to the Slave, server2, and further from the Master, server2, to the Slave, server3. (This chain could continue further, but regardless of its length it obeys the rules described in this Section.) In this scenario the server2 will support IXFR to the server3 as long as it receives IXFR from the server1.

Dynamic Update

In a conventional DNS implementation, if the authoritative information must be changed, the network administrator has to edit the appropriate zone file manually. The Domain Name System was originally designed to support queries of a statically configured database. While the data was expected to change, the frequency of those changes was expected to be fairly low, and all updates were made as external edits to a zone’s primary master file.

The advent of dynamic, automated IP addressing using DHCP and related

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