On Thu, Mar 26, 2020 at 12:02:45PM +0000, Simon Kelley wrote: > On 23/03/2020 13:25, Chris Green wrote: > > > > I'm running dnsmasq version 2.76 on a Raspberry Pi. The systems > > seeing the delay when they send a query are (mostly) running xubuntu > > 19.10. > > > > The delay only occurs when querying names on the LAN, requests for > > external names run normally. It makes no difference whether I give a fully > > qualified name or just the machine name (the domain gets added by the > > 'search' option in /etc/resolv.con anyway). > > > > It appears to be something to do with IPV6 and AAAA records (or lack > > of them) that causes the issue but I'm still stumped as to how to fix > > it. > > > > Having set 'log-queries=extra' in /etc/dnsmasq.conf I see the > > following in /var/log/syslog when I query (using 'host') the name > > 'esprimo' twice from my laptop after booting (booting the laptop that > > is). > > [snip log] > > > > So for some reason first time round the querying system asks > > repeatedly for the AAAA record, then waits 5 seconds, asks again and > > then gives up. But it only does this the first time it sends the > > query. (I suspect that the delay re-occurs after a long idle time but > > I can't reproduce the delay by clearing the systemd resolvctl cache) > > > > I realise this probably isn't directly a dnsmasq problem but I'd > > really appreciate any suggestions or workarounds that might help me > > fix this issue. I can easily add more debug flags or configuration if > > they might help. > > > > > Dnsmasq looks to be doing the right thing here, if one assumes that what > it sends is the same as what it logs (and I have not reason to believe > it isn't). > > Given the MX query, it looks like the originator may be a mail transfer > agent (sendmail, exim and friends). Can you determine what is making the > queries and maybe configure it not to use IPv6? > > Yes, thank you Simon. It just dawned on me (thinking about it in bed last night) that the log only shows what dnsmasq *sent* and not what was received or acted on at the other end. I think my next job is probably to set up wireshark or something like it and actually observer what is going in and out of the client system.
-- Chris Green _______________________________________________ Dnsmasq-discuss mailing list Dnsmasqemail@example.com http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss