DNS on Windows Server 2003, 3rd Edition

Secondary Servers

You can have some of your secondaries load zone data from other secondary name servers instead of from a primary name server. The secondary name server can’t tell if it’s loading from a primary or another secondary. It’s only important that the name server serving the zone transfer is authoritative for the zone. There’s no trick to configuring this. Instead of specifying the IP address of the primary in the secondary’s configuration, you simply specify the IP address of another secondary

When you go to this second level of distribution, though, be aware that it can take up to twice as long for the data to percolate from the primary name server to all the secondaries. Remember that the refresh interval is the period after which the secondary servers check to make sure that their zone data is still current. Therefore, it can take the first-level secondary servers the entire length of the refresh interval to get a new copy of the zone from the primary master server. Similarly, it can take the second-level secondary servers the entire refresh interval to get a new copy of the zone from the first-level secondary servers. The propagation time from the primary master server to all the secondary servers can therefore be twice the refresh interval.

Fortunately, using the DNS NOTIFY feature, which we’ll describe in Chapter 11, avoids this delay. This feature is on by default and triggers zone transfers soon after the zone is updated on the primary master. Unfortunately, ...