DDNS, Notify and IXFR

Kevin J. Dunlap kevind at metaip.checkpoint.com
Thu Aug 12 16:48:52 UTC 1999

This discussion is likely to move over to namedropper, but I'll start it
here incase it's an implementation problem. Here is the configuration.

You have five name servers for a dynamic domain. You have continuous
updates happening at about a rate of four updates a second. You have IXFR
running between the Primary and the secondaries and notify is turned on.

Update packets start coming into the primary. Serial number increments
on primary and notify messages go to secondaries. Secondaries start requesting
IXFR. Update packets are still coming in. IXFR triggers the serial
number to increment and another round of notifies fire off. What we end up
seeing is that the serial number starts incrementing with every update because
a secondary requests an IXFR at about the same rate the update packets arrive.

When you start seeing the fan out of the packets you start to wonder if
this sequence of events will start to consume the network. One update 
packet goes
from the originator to each of the five name servers. The primary ends up 
sending a
packet to the other four name servers. Those four send an IXFR request to 
the primary.
These generate four more notifies that start four more IXFRs. And the loop 

Do we need a throttle on the rate notify messages go out?
Or do we just turn off notify and let the TTL's do the work?


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