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Groups > linux.debian.bugs.dist > #763930

Bug#836236: prosody: doesn't try IPv4 when IPv6 fails

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Matthew Wild <mwild1@gmail.com> (2016-09-01):
> On 31 August 2016 at 23:25, Cyril Brulebois <kibi@debian.org> wrote:
> > So it looks to me like it could be an initial DNS issue (partial and/or
> > no resolution depending on the domain) which happened at start-up time,
> > and failed/incomplete resolutions weren't attempted again later on.
> >
> > Would this seem even remotely plausible?
> 
> Yes, this is plausible. I've seen this issue before on some servers,
> but I haven't been able to track it down to a cause. One theory is
> that if you log into a freshly-started server, and you have a lot of
> contacts on remote domains, it triggers a burst of DNS requests. DNS
> being UDP, which is lossy, some of the DNS requests fail due to packet
> loss caused by temporary network congestion.

That theory doesn't seem to likely here, since the total of remote
domains is likely under 20 (maybe even 10)…

Maybe I'll get more information at the next reboot, I'll update this bug
report then.

> Eventually the failed s2s connections do establish - they will be
> retried as soon as you change status for example, or if any of your
> remote contacts change status or try to send you a message.

OK. But those won't generate a new DNS request AFAICT? Some contacts
appeared offline (with DNS failure as a reason) for a whole day after
the initial DNS failure; until I restarted prosody manually.


KiBi.

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Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Cyril Brulebois <kibi@debian.org> - 2016-08-31 23:30 +0200
  Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Matthew Wild <mwild1@gmail.com> - 2016-09-01 00:00 +0200
    Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Cyril Brulebois <kibi@debian.org> - 2016-09-01 00:10 +0200
      Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Cyril Brulebois <kibi@debian.org> - 2016-09-01 00:30 +0200
        Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Matthew Wild <mwild1@gmail.com> - 2016-09-01 10:40 +0200
          Bug#836236: prosody: doesn't try IPv4 when IPv6 fails Cyril Brulebois <kibi@debian.org> - 2016-09-01 17:20 +0200

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