forwarders order

[Mark Andrews]

It is smoothed RTT.  Forwarders however have highly variable RTT as the records usually needs
to be looked up from the authoritative servers so what you end up measuring is RTT +
resolution time.  RRsets expire at the same time on both the local caching server and the
forwarders.


> On 21 Aug 2025, at 22:07, DEMBLANS Mathieu <demblans.m at numihfrance.fr> wrote:
> 
> Hello,
> Anyone know how forwarder is choosen when there is several configured ?
> Threads about this subject I found talk about RTT but we doesn’t observe these.
> It looks more like a round robin.
> I have tested the response time of the forwarders, our 2 locals servers respond in 2ms, the 2 others, that are remote, respond in 14ms but if I check the DNS traffic between the NS requested and the forwarders contacted I have a 26/26/23/23% repartition, 26% for remotes forwarders.
> We use bind 9.18.24
> Any idea about how it should work?
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Mark Andrews, ISC
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