On Thu, 2014-04-03 at 21:37 +0100, Simon Kelley wrote: > On 02/04/14 22:32, Olivier Mauras wrote: > > > > > > On Mon, 2014-03-31 at 12:59 +0200, Olivier Mauras wrote: > >> Hello, > >> > >> Is it thinkable to allow a per entry TTL override system ? I have > >> actually two different needs that i'd like to discuss. First > >> NXDOMAINS. I'd like to cache NXDOMAIN from some forwarded domains > >> to a specific value. Cache time based on default SOA TTL may be > >> too long in some cases and requires a manual cache refresh :( > >> Easy example: Infra team provisions a new server and ping the > >> hostname asked to see if it's not already taken - Yes they could > >> act differently It's not, so result is cached and will stay for > >> 1H - default SOA TTL. Server provisioning takes 10mn, and > >> hostname is still cached as NX for 50mn :( > >> > >> Second is entry override. Some specific DNS entries could have a > >> different TTL than the default one - But not globally per entry > >> gives much more flexibility :) > >> > >> > >> Would that make sense to have a binding for request replies - > >> like the dhcp lua script support - or would this make more sense > >> as specific harcoded options? If this makes any sense at all > >> indeed :) > >> > >> > >> Thanks, Olivier > >> > >> > >> _______________________________________________ Dnsmasq-discuss > >> mailing list Dnsmasq-discuss@lists.thekelleys.org.uk > >> http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > > > > Seemed like i had a double neg-ttl declared in my config and my > > command line at the same time which make it to not be correctly > > handled... Also seems that no matter what neg-ttl is set to, the > > first NXDOMAIN on a cold cache, always get the SOA TTL, am i > > missing something ? > > neg-ttl does not override the SOA TTL, it provides a TTL for NXDOMAIN > if the upstream server doesn't include an SOA. (Lots of ISP > nameservers seem to strip that information for "bandwidth saving") If > you upstream servers include SOA, as they should, then neg-ttl will > have no effect. > > > > > > Any feedback on per entry TTL override > > I'm not sure about that, it seems to me to be fiddly and prone to > errors. You first example could be fixed by using --no-negcache. It > would be less efficient, but it would always work. If you're going to > set a TTL in that case, what's the correct value that will always > work? I don't think there is one. > > I'm interested in other opinions. > > > Cheers, > > > Simon. > > > > > > > Thanks, Olivier > > > > > > > > _______________________________________________ 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
True that no-negcache would fix my first example, but wouldn't caching for a definite time be more efficient? I actually have weird behavior when cascading dnsmasq instances. 127.0.0.1 forwarding to a dnsmasq instance, forwarding to an unbound server... 127.0.0.1 on first query receives the SOA TTL, but as the forwarded dnsmasq instance has cached, it returns 0 as TTL. So clearing cache on 127.0.0.1 and asking again same query will return with neg-ttl as the TTL. I agree it's pretty particular but having a "neg-cache-ttl" would prevent this _and_ be efficient enough :) That was for NXDOMAINS, what about overriding TTL for standard entry? opinions? Thanks, Olivier
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