[Pdns-users] pdns-recursur 4.4: host unknown after some time with no clear reason

Jan Huijsmans bofh at koffie.nu
Wed Jun 1 10:32:32 UTC 2022

Hi Frank,

On Wed, 1 Jun 2022 11:23:16 +0200
"frank at tembo.be" <frank at tembo.be> wrote:
> When this fails, could you run a dig command for a domain after
> activating trace for that domain? (See
> https://doc.powerdns.com/recursor/manpages/rec_control.1.html?highlight=trace-regex
> <https://doc.powerdns.com/recursor/manpages/rec_control.1.html?highlight=trace-regex>)
> I'd like to see the full trace, but my guess would be all the
> upstream / root name servers have been marked as too slow to be
> reliable by PowerDNS.

I'm not allowed to give a full trace, NDA and stuff. The rec_control
command can help though. I'll see what I can dig up from the
environment when I'm able to access it again.

The slow speed could be the cause, as there are low speed high latency
links between the recursor and the root servers. How do I disable that
speed check in PowerDNS?

> Also, I would recommend upgrading to a more recent version,
> especially as 4.5 adds goodies such as
> https://doc.powerdns.com/recursor/settings.html#non-resolving-ns-max-fails
> <https://doc.powerdns.com/recursor/settings.html#non-resolving-ns-max-fails>.

Alas, upgrading is not an option, as the environment is 'frozen'. The
environment needs to work as-is for at least 1.5 years. All we can do
is tweak settings. I'm already happy we could abandon 4.0 last year.


Jan Huijsmans              bofh at koffie.nu

... cannot activate /dev/brain, no response from main coffee server

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