[dns-operations] max-clients-per-query limit

[Witold Krecicki]

The limit is 'for one recursive resolution' - if BIND receives a query
for something it's already processing (and the answer is not in cache)
then it'll not start a new resolution but add this query to a list of
clients waiting for the result of the one already being processed.
clients-per-query is the default limit on the number of clients waiting
for a single result, it can be dynamically changed by BIND but it'll
never exceed max-clients-per-query. 
Mark Andrews explained it quite nicely here:
https://lists.isc.org/pipermail/bind-users/2011-March/083330.html
--
wpk

On 04.04.2017 20:03, Shawn Zhou wrote:
> Hi Evan,
>
> How long is the time window that BIND uses to calculate the identical
> lookups?
> Is it over 1-minute window? or 5-minute window?
>
>
> Thanks,
> Shawn
>
>
> ------------------------------------------------------------------------
> *From:* Evan Hunt <each at isc.org>
> *To:* Shawn Zhou <shawnzhou00 at yahoo.com>
> *Cc:* "dns-operations at lists.dns-oarc.net" <dns-operations at dns-oarc.net>
> *Sent:* Wednesday, March 22, 2017 10:07 PM
> *Subject:* Re: [dns-operations] max-clients-per-query limit
>
> On Wed, Mar 22, 2017 at 10:05:35PM +0000, Shawn Zhou wrote:
>
> > What happens when max-clients-per-query is reached? say, we have 120
> > duplicate requests and the max-clients-per-query is set to 100. Do
> the 20
> > "extra" requests got dropped or get timeouts or they will be part of
> next
> > grouped requests?
>
>
> They're dropped.
>
> -- 
> Evan Hunt -- each at isc.org <mailto:each at isc.org>
> Internet Systems Consortium, Inc.
>
>
>
>
>
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