loosing packets

Peter Dambier peter at peter-dambier.de
Thu Apr 20 12:42:39 UTC 2006

Tom Schmitt wrote:
>>--- Ursprüngliche Nachricht ---
>>Von: Peter Dambier <peter at peter-dambier.de>
>>Tom Schmitt wrote:
>>>My question is:
>>>Does anyone know of another reason for the named loosing UDP-Packets
>>>than too much load?
>>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throwing out all outdated records.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 
>>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
> Thank you very much for your explanaition. My server is indeed a slave with
> many zones which are updated quite often (IXFR from the master).
> That leads me to a more specific question: With the option "transfers-per-ns
> 4;" I told the named not to get more than 4 zones from the master at once.
> Would it help, to have more the 4 threads, so while four threads are deaf
> because they are busy with the updates, the other threads could answer the
> incoming requests?
> Or, same question, another phrasing: Is really the hole slave deaf while
> updating a zone or only the thread which is doing the update?
> Thanks,
> Tom.

It is only a guess, I think for the garbadge collection the whole Bind must
be locked or it would not be able to return memory properly.

Nevertheless I have seen older Bind leaking.

Memory management is needed both in updating zone data and in the resolver.

Maybe looking for tinydns, the djbdns authoritative server would help you.
Maybe looking for powerdns would help you.

Tinydns reads its data from file and only caches temporaryly. You can
update the data without stopping and restarting the server. I have not
seen the bind kind of blackouts. Reading and understanding Bernstein
is a different matter so :)

Kind regards
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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