On 23/03/2020 13:25, Chris Green wrote: > I'm still trying to work out why the first DNS query to dnsmasq > running on a server on my LAN suffers a 5 second delay but subsequent > requests don't see the delay. > > 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). > > First 'host esprimo':- > Mar 23 12:59:06 newdns dnsmasq[4256]: 54 192.168.1.92/56886 query[A] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 54 192.168.1.92/56886 /etc/hosts > esprimo.zbmc.eu is 192.168.1.3 > Mar 23 12:59:06 newdns dnsmasq[4256]: 55 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 55 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 56 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 56 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 57 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 57 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 58 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 58 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 59 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 59 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 60 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 60 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 61 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 61 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 62 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 62 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 63 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 63 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 64 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 64 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 65 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 65 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 66 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 66 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 67 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 67 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 68 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 68 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 69 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 69 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 70 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 70 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 71 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 71 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 72 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 72 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 73 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 73 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 74 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 74 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 75 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 75 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 76 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 76 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 77 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 77 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:06 newdns dnsmasq[4256]: 78 192.168.1.92/37906 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:06 newdns dnsmasq[4256]: 78 192.168.1.92/37906 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:11 newdns dnsmasq[4256]: 79 192.168.1.92/35896 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:11 newdns dnsmasq[4256]: 79 192.168.1.92/35896 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:11 newdns dnsmasq[4256]: 80 192.168.1.92/48696 query[MX] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:11 newdns dnsmasq[4256]: 80 192.168.1.92/48696 config > esprimo.zbmc.eu is NODATA > > > Second 'host esprimo':- > Mar 23 12:59:25 newdns dnsmasq[4256]: 91 192.168.1.92/56179 query[A] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:25 newdns dnsmasq[4256]: 91 192.168.1.92/56179 /etc/hosts > esprimo.zbmc.eu is 192.168.1.3 > Mar 23 12:59:25 newdns dnsmasq[4256]: 92 192.168.1.92/59553 query[AAAA] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:25 newdns dnsmasq[4256]: 92 192.168.1.92/59553 config > esprimo.zbmc.eu is NODATA-IPv6 > Mar 23 12:59:25 newdns dnsmasq[4256]: 93 192.168.1.92/32976 query[MX] > esprimo.zbmc.eu from 192.168.1.92 > Mar 23 12:59:25 newdns dnsmasq[4256]: 93 192.168.1.92/32976 config > esprimo.zbmc.eu is NODATA > > > 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? Simon. _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
