On 16/02/16 12:48, Comerma Pare, Antoni wrote: > Sorry for my late answer, but our corporate email server seems to dislike > mailing lists and ate the message up. Searching the web I've found the > answer. That's why I'm answering to my previous message > > The cname can be resolved > > $ dig @localhost 10m.pub.dtvc.local > > ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.37.rc1.el6_7.6 <<>> @localhost > 10m.pub.dtvc.local > ; (2 servers found) > ;; global options: +cmd > ;; Got answer: > ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34642 > ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0 > > ;; QUESTION SECTION: > ;10m.pub.dtvc.local. IN A > > ;; ANSWER SECTION: > 10m.pub.dtvc.local. 3600 IN CNAME lbback.pub.dtvc.local. > lbback.pub.dtvc.local. 3600 IN A 10.111.0.26 > > ;; Query time: 0 msec > ;; SERVER: 127.0.0.1#53(127.0.0.1) > ;; WHEN: Tue Feb 16 12:34:04 2016 > ;; MSG SIZE rcvd: 87 > > Using wireshark I've seen the query for A and AAAA records and the response > for A and a NXDOMAIN response for the AAAA. > We tried with a newer version but no improvement.
If the answer is really NXDOMAIN then something's wrong. an NXDOMAIN answer for (eg) AAAA 10m.pub.dtvc.local means that 10m.pub.dtvc.local _doesn't_exist_, so a query for A records of the same name, can only return NXDOMAIN too. The logs you posted originally seem to indicate that dnsmasq is seeing answers with the CNAMEs but no A or AAAA records. If A records had been present, the IP address in them would have been logged. That's different from the dig output above, so something odd is happening, possibly with the answers that dnsmasq is getting from upstream. I'd try and resolv that first. Cheers, Simon. > > > Kind regards > > ---------------------- > Simon wrote > > The simplest explanation for this is that 10m.pub.dtvc.local is a > CNAME which points to a non-existant domain. If that was the case, > then the cache entry would last only as long as the domain's negative > TTL, which could be much shorter. > > > What answer do you get when you run > > > dig 10m.pub.dtvc.local > > Cheers, > > Simon. > > De: Comerma Pare, Antoni > Enviat: dimecres, 3 / febrer / 2016 11:48 > Per a: 'dnsmasq-discuss@lists.thekelleys.org.uk' > Tema: Some dns entries are not cached properly > > Hi, > > We are experiencing some weird behavior when using dnsmasq as dns cache. We > are using it in a webserver that makes lots of dns request for just a bunch > of backend servers, so the # of cache entries is usually very low, but for > some of these entries, dnsmasq is forwarding more requests than expected. > > Here there is an extract of the requests answered by dnsmasq > > awk -f dns.awk /tmp/dnsmasq.log > name | nb | forwarded | > answered with cache > 1m.pub.dtvc.local | 296 | 146 | > 150 > config.pub.dtvc.local | 434 | 197 | > 242 > web01.pub.dtvc.local | 10 | 5 | > 5 > 24h.pub.dtvc.local | 12 | 6 | > 6 > lbfront-static.pub.dtvc.local | 31 | 6 | > 25 > lbfront-php-old.pub.dtvc.local | 648 | 17 | > 631 > memc01.pub.dtvc.local | 62286 | 28 | > 62258 > 30m.pub.dtvc.local | 13784 | 2096 | > 11694 > 10m.pub.dtvc.local | 17702 | 2312 | > 15406 > 10s.pub.dtvc.local | 6522 | 2461 | > 4067 > > DNS TTL is 3600 for all entries > 10s.pub.dtvc.local, 10m.pub.dtvc.local, 30m, 24h have a low cache hit ratio > (much more than expected) , while memc01.pub.dtvc.local has a high hit ratio > (as expected) > The problematic entries are CNAMES, A records work as expected > The apache webserver is making requests for A and AAAA addresses. The DNS > server returns NODATA-IPV6 for AAAA requests > > An extract from the logfile, for 10s.pub.dtvc.local shows a lot of requests > for A and AAAA. It seems than a great part of A requests are forwarded, while > AAAA records are mainly cached. > > This is for entry 10s.pub.dtvc.local > Feb 3 10:32:23 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:23 dnsmasq[1931]: forwarded 10s.pub.dtvc.local to 172.26.10.1 > Feb 3 10:32:23 dnsmasq[1931]: reply 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:23 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:23 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:25 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:25 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:25 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:25 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:27 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:27 dnsmasq[1931]: forwarded 10s.pub.dtvc.local to 172.26.10.1 > Feb 3 10:32:27 dnsmasq[1931]: reply 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:27 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:27 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:27 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:27 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:27 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:27 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:30 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:30 dnsmasq[1931]: forwarded 10s.pub.dtvc.local to 172.26.10.1 > Feb 3 10:32:30 dnsmasq[1931]: reply 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:30 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:30 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:37 dnsmasq[1931]: query[A] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:37 dnsmasq[1931]: forwarded 10s.pub.dtvc.local to 172.26.10.1 > Feb 3 10:32:37 dnsmasq[1931]: reply 10s.pub.dtvc.local is <CNAME> > Feb 3 10:32:37 dnsmasq[1931]: query[AAAA] 10s.pub.dtvc.local from 127.0.0.1 > Feb 3 10:32:37 dnsmasq[1931]: cached 10s.pub.dtvc.local is <CNAME> > > This is for 10m.pub.dtvc.local > Feb 3 09:57:06 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:06 dnsmasq[58096]: forwarded 10m.pub.dtvc.local to 172.20.1.1 > Feb 3 09:57:06 dnsmasq[58096]: reply 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:06 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:06 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:06 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:06 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:06 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:06 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:07 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:07 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:07 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:07 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:07 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:07 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:07 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:07 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: forwarded 10m.pub.dtvc.local to 172.20.1.1 > Feb 3 09:57:09 dnsmasq[58096]: reply 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: forwarded 10m.pub.dtvc.local to 172.20.1.1 > Feb 3 09:57:09 dnsmasq[58096]: reply 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:09 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:09 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:10 dnsmasq[58096]: query[A] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:10 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > Feb 3 09:57:10 dnsmasq[58096]: query[AAAA] 10m.pub.dtvc.local from 127.0.0.1 > Feb 3 09:57:10 dnsmasq[58096]: cached 10m.pub.dtvc.local is <CNAME> > > Dumping the cache contents, it shows > > Feb 3 09:51:28 dnsmasq[58096]: cache size 1000, 0/6659 cache insertions > re-used unexpired cache entries. > Feb 3 09:51:28 dnsmasq[58096]: queries forwarded 3359, queries answered > locally 71834 > Feb 3 09:51:28 dnsmasq[58096]: server 172.20.1.1#53: queries sent 3359, > retried or failed 2 > Feb 3 09:51:28 dnsmasq[58096]: Host > Address Flags Expires > Feb 3 09:51:28 dnsmasq[58096]: backend.pub.dtvc.local > CF Wed Feb 3 10:00:58 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbfront-static.pub.dtvc.local > 10.111.0.23 4F Wed Feb 3 10:24:42 2016 > Feb 3 09:51:28 dnsmasq[58096]: big.dtvc.local > big06.dtvc.local CF Wed Feb 3 10:07:17 2016 > Feb 3 09:51:28 dnsmasq[58096]: 10m.pub.dtvc.local > CF Wed Feb 3 10:47:07 2016 > Feb 3 09:51:28 dnsmasq[58096]: 1m.pub.dtvc.local > CF Wed Feb 3 10:03:46 2016 > Feb 3 09:51:28 dnsmasq[58096]: 24h.pub.dtvc.local > CF Wed Feb 3 10:21:52 2016 > Feb 3 09:51:28 dnsmasq[58096]: memc02.pub.dtvc.local > 6F N Wed Feb 3 10:00:38 2016 > Feb 3 09:51:28 dnsmasq[58096]: memc02.pub.dtvc.local > 10.111.0.12 4F Wed Feb 3 10:00:38 2016 > Feb 3 09:51:28 dnsmasq[58096]: memc01.pub.dtvc.local > 6F N Wed Feb 3 10:00:38 2016 > Feb 3 09:51:28 dnsmasq[58096]: memc01.pub.dtvc.local > 10.111.0.11 4F Wed Feb 3 10:00:38 2016 > Feb 3 09:51:28 dnsmasq[58096]: > 172.29.120.101 4 R NX Wed Feb 3 10:35:26 2016 > Feb 3 09:51:28 dnsmasq[58096]: > 172.26.60.50 4 R NX Wed Feb 3 10:30:01 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbfront-php-old.pub.dtvc.local > 6F N Wed Feb 3 10:05:24 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbfront-php-old.pub.dtvc.local > 193.104.51.29 4F Wed Feb 3 09:52:01 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbback.pub.dtvc.local > 10.111.0.26 4F Wed Feb 3 10:10:55 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbback.pub.dtvc.local > 6F N Wed Feb 3 10:00:39 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbfront-web-old.pub.dtvc.local > 6F N Wed Feb 3 10:00:40 2016 > Feb 3 09:51:28 dnsmasq[58096]: lbfront-web-old.pub.dtvc.local > 10.111.0.36 4F Wed Feb 3 10:00:40 2016 > Feb 3 09:51:28 dnsmasq[58096]: config.pub.dtvc.local > CF Wed Feb 3 10:00:44 2016 > Feb 3 09:51:28 dnsmasq[58096]: big06.dtvc.local > 6F N Wed Feb 3 09:48:34 2016 > Feb 3 09:51:28 dnsmasq[58096]: big06.dtvc.local > 172.26.11.141 4F Wed Feb 3 10:07:16 2016 > Feb 3 09:51:28 dnsmasq[58096]: 30m.pub.dtvc.local > lbback.pub.dtvc.local CF Wed Feb 3 10:00:37 2016 > > I've noticed that: > > · One of the problemàtic entries, 10s.pub.dtvc.local does not appear > > · 10m.pub.dtvc.local does not have "Address" > > · 30m.pub.dtvc.local in contrast, has "address"= > lbback.pub.dtvc.local. In fact, all 3 entries are CNAMES pointing to > lbback.pub.dtvc.local > > These are the symptoms, but we don't have explanation. We've digged into the > man page, the lists, google, and no clues. > Toni Comerma > SECA Infraestructures i Comunicacions > c/ de la TV3 s/n · 08970 Sant Joan Despí (Baix Llobregat) > Telèfon: +34 935.522.328 > Mòbil: +34 627.481.650 > www.tv3.cat<http://www.tv3.cat/> > > > > > > > > > > _______________________________________________ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > _______________________________________________ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
