loosing packets

Peter Dambier peter at peter-dambier.de
Wed Apr 19 18:11:14 UTC 2006

Tom Schmitt wrote:
> Hi,
> I'm running Bind 9.3.2 on Solaris10(Sparc) and have problem with loosing
> packets.
> Most times a DNS-request is answered properly, but sometimes you'll get a
> timeout instead. I looked into the problem and found that I'm loosing
> UDP-Packets (UDP-Buffer-Overflow). Looking at "kstat -p
> ip:0:ip:udpInOverflows 10" showed me, that I'm loosing about one packet out
> of 100.
> Increasing the Buffersize from 2 MB to 4 MB didn't change anything.
> Googeling for this problem brought the suspicion, that the load is too much
> for the server so it cannot handle all the requests. So I tried to confirm
> this suspicion: I did a load-test with queryperf and put ten times of the
> normal load on the server, doing more than 100 thousend queries in about 25
> seconds. But what did I see? There was no increase of packet-loss. Instead,
> in this short period of time, there was not one single packet lost. So it
> seems to me that this is not a simple load-problem.
> My question is:
> Does anyone know of another reason for the named loosing UDP-Packets than
> too much load?
> Thanks for any help,
> Tom.

A Bind 9 resolver does shut its ears when it sorts its resolver cache
throwing out all outdated records. The bigger the used cache the longer
the blackout.

A Bind 9 authoritative slave turns you a deaf ear when it looks at its
master for updates and when it transfers the new zonefile from the master.
More zones to slave means more times it will blackout. Longer zones will
take longer to load. The blackout will be longer.

Peter and Karin

Peter and Karin Dambier
The Public-Root Consortium
Graeffstrasse 14
D-64646 Heppenheim
+49(6252)671-788 (Telekom)
+49(179)108-3978 (O2 Genion)
+49(6252)750-308 (VoIP: sipgate.de)
mail: peter at peter-dambier.de
mail: peter at echnaton.serveftp.com

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