[dnsdist] Latency value under showServers()

[Nigel H]

Thanks Bert,

You are 100% correct!  I used grepq as you suggested and indeed I have
queries which took over 100ms plus the small sample size explains this.
Out of curiosity is there a more elegant way to extract queries using grepq
for external requests?  I did the following to exclude internal domains:

        dnsdist -e "grepq('.')"  | egrep -v '<internal domain>|<another
internal domain>|arpa'


Nigel.

On 19 March 2018 at 11:39, bert hubert <bert.hubert at powerdns.com> wrote:

> On Mon, Mar 19, 2018 at 11:30:08AM +0000, Nigel H wrote:
> > I'm seeing a discrepancy when i run showServers() in dnsdist.  Our
> internal
> > pool of dns servers appears correct and monitoring shows the odd spike in
> > latency but our external pool (opendns) seems to just keep increasing in
> > value.  The documentation states its the latency for this servers in
> > milliseconds but when I test using dig I'm seeing normal resolution times
> > 1-8ms mostly but dnsdist reports latency like below (27ms).
>
> Hi Nigel,
>
> The likely reason for the increase is that opendns has only received 169
> and
> 148 queries so far.  This means the weighted average latency still includes
> a lot of 0.
>
> Eventually, you should see the opendns latency plateau.
>
> With 'grepq()' you should be able to find the queries being sent to
> opendns,
> and how long dnsdist thought they were taking.
>
> You could then perhaps retry those queries with 'dig' to see how long they
> take. 27ms is not unreasonable for mostly cache misses.
>
> > Can someone confirm its meaning?  Is it an average latency based an
> amount
> > of queries to this server or is it the highest latency seen?  Also does
> > dnsdist incorporate the latency of the health check?
>
> The last part, no. First part, it is average.
>
>         Bert
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.powerdns.com/pipermail/dnsdist/attachments/20180319/b9660e4b/attachment.html>