DNS response time

[Mike B]

In message <cok6gr$2lhr$1 at sf1.isc.org>, phn at icke-reklam.ipsec.nu writes
>afaf <afaf.e at menara.ma> wrote:
>>Hi;
>>I wish to know if a significant number of created zones in a DNS server 
>>can increase the DNS response time .
>
>Response time will start a significamt increase when system resources
>are exhausted ( memory,swap, network bandwidth etc). Until then there is a 
>small increase in responsetime, but you should not be affected.
>
>The only way to know is to populate a lab and start testing.
>
>
>>Best regards;
>
>

This is interesting. We have a particular pair of heavily used (for us) DNS
servers. We estimate between 80-200 queries a second are being
handled by these, unfortunately the team that specced the hardware
have now told us they never actually benchmarked anything, it was just
finger in the air stuff. We've been getting nervous that BIND has been
getting near the limits of the server, however vmstat shows nothing
untoward, and if this *is* the definitive test for BIND performance then
it's reassured us somewhat. Are there any docs anywhere which
explain what resources BIND uses?

The reason we think BIND has been pushing the box is seemingly
random cache corruptions that only a restart will cure, we have a few
pairs of DNS servers on identical architecture and it's only the one
under "heavy" load that shows this, investigations are continuing.

cheers

--
Mike