Geert, What is the meaning of this?
On Tue, Mar 17, 2020, 1:48 AM Geert Stappers <stapp...@stappers.nl> wrote: > On Mon, Mar 16, 2020 at 08:31:17PM -0500, Sasha Litvak wrote: > > I couldn't find a specific answer anywhere so hopefully someone has a > > clue on this list > > > > We are using dnsmasq on our servers as a caching dns solution. > > > > Most of our domains are resolved by a wildcard record like this > > > > $TTL 3600 ; 1 hour > > A 10.10.10.23 > > $ORIGIN example.net. > > * CNAME excontainers > > excontainers CNAME exservice.service.consul > > > > dnsmasq handles resolution of .consul domain directly but the DNS > > server itself also forwards .consul to consul servers. > > > > I added min-ttl 5s to decrease the number of queries to consul > > > > So when I do dig foo.example.net @127.0.0.1 I get > > > > foo.example.net. 3600 IN CNAME excontainers.example.net. > > excontainers.example.net. 3600 IN CNAME exservice.service.consul. > > exservice.service.consul. 5 IN A 10.0.48.13 > > > > Now we often need to migrate subdomains by pointing them to a > > different consul cluster. So our script uses nsupdate and creates a > > dynamic DNS record resulting in this reply > > > > foo.example.net. 60 IN CNAME exservice2.service.consul. > > exservice2.service.consul. 5 IN A 10.0.48.35 > > > > So we have a record that is more explicit and it takes precedence over > > wild card. On servers with little traffic, domain switch happens > > within a few seconds, but on the main busy server with 100s of queries > > a second, it takes an hour for dnsmasq to change its cache. We see > > dnsmasq sending requests to the DNS server getting correct new records > > but still sending the old cached records to a client. > > > > When we are going back from distinct to default wild card (removing > > distinct record in DNS) cache change happens almost immediately (a > > couple of seconds) regardless of how busy the server is. > > > > Sorry for the long description but I would like to find out a reason > > why during switching from wild card to more explicit record dnsmasq > > cache update takes such a long time. > > $ host -t ns org > org name server d0.org.afilias-nst.org. > org name server b2.org.afilias-nst.org. > org name server a0.org.afilias-nst.info. > org name server a2.org.afilias-nst.info. > org name server b0.org.afilias-nst.org. > org name server c0.org.afilias-nst.info. > $ host -t ns consul > Host consul not found: 3(NXDOMAIN) > $ > > > _______________________________________________ > Dnsmasq-discuss mailing list > Dnsmasqemail@example.com > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss >
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