Multi-Master and NOTIFY

Tom Daly tom at
Thu Nov 30 17:07:28 UTC 2006


We are running slaves with multi-masters for some of our clients. Our 
slaves are running on BIND 9.3.1. Consider the following typical scenario:

Client has two master servers, and, both of 
which are configured as masters in our slave zone declaration; masters {;; }.

There have been cases where the zone file on is not correctly 
being updated by the zone generator, so as updates occur, the zone's 
serial number is not being incremented. However, the second master,, is properly updating and has incremented it's serial number.

When this happens, our slave servers will receive a notify from, will queue a refresh check, and then start to check the 
masters in order. When BIND queries, it discovers that it is 
up to date from's point of view, and stops processing.

Is there any way to force BIND to search all masters to get updated to the 
serial number it received in the NOTIFY packet? Or can I force BIND to 
zone transfer from the server which it received the NOTIFY from?

According to Paul Vixie on 2005-02-02 14:56:38, it should be doing this:

"it will try them all, transfer only from a master offering the best 
currently available serial number.  this is tricky given "sequence number 
arithmetic" and 32-bit rounding."

However, I do not see this happening. As a side note, the serial numbers 
being used are not on any sort of 32-bit rounding boundary.

Can anyone shed some light on this? I haven't seen anything in the 
archives that point to this issue.

Tom Daly

Thomas J. Daly
tom at
Dynamic Network Services, Inc.

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