Primary Reloading and Secondary Zones Expiring

[Mark_Andrews at iengines.com]

	Firstly, reasonable expire values are of the order of weeks
	not days.  Expire is the time the secondary will continue to
	answer without being able to contact the primary.

	Also the following bug could stop zones being transfered.

 527.   [bug]           we were not reliably reaping our children.

	There have also been other fixes which help with large sites
	in this area.

	I would upgrade both boxes.

	Mark

> All-
> 
> I'm a little confused about secondary zone expiration and am looking for
> some help.
> 
> I have 2 primary DNS servers running BIND 8.2.1 (for load balancing and
> redundancy) and a secondary DNS server running BIND 8.1.2.  These servers
> are SOA for thousands of domains.  By default I'm letting DNS Notify handle
> the new/modified zones and their transfers to the secondary.
> 
> I was recently checking the secondary server to make sure that new zones
> were getting transfered.  I read in "DNS and BIND" that DNS notify generally
> causes the zone transfers to happen within 15 minutes.  Some of the new
> zones were taking 3 and 4 days to transfer to the secondary.  I then turned
> on debugging level 1 on the secondary server and found what looked like the
> server being overloaded with zone maintenance, ie., expiring and tranfering
> secondary zones.
> 
> After discovering this I changed all zone files from a 24 hour EXPIRE to 7
> days, and a 4 hour TTL to 24 hours.  I then ran a script on the secondary
> server to manually run named-xfer against all zones and used the serial
> number of 0 to force transfers, after which I rebooted the secondary server
> to give it a "fresh" start.  I expected to see the zone maintenance
> decrease greatly and new zones added to notify and transfer in a more
> reasonable amount of time.  What I see now is that some of those new zones
> are still taking days to transfer to the secondary and more zone maintenance
> than I would have expected.
> 
> The only thing that I can see that may affect the way all of the zones are
> being handled is that the primary server gets reloaded on a regular interval
> to rebuild named.conf and propogate the new/modified/deleted information to
> the other primary server.  We also reload the secondary on a regular
> interval to pick up the changes made to named.conf.  These reloads happen
> because there are zone additions/modifications/deletions every day.
> 
> This all leads me to some questions:
> 
> 1. If we reload the primary server does that cause the primary to notify the
> secondary to transfer zones?
> 2. If we reload the secondary server does that somehow cause the secondary
> zones to expire and need to be transfered?
> 3. Is there a better way of handling all of the
> additions/modifications/deletions that occur on a daily basis?
> 
> Thanks in advancefor any help and/or suggestions.
> 
> ==========================
> Peter Goode
> Exodus Professional Services
> peter.goode at exodus.net
> 
--
Mark Andrews, Internet Engines Inc. / Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at iengines.com