[dns-operations] negative caching weirdness

[Robert Edmonds]

Robert Edmonds wrote:
> Matthew Pounsett wrote:
> > On 22 April 2016 at 15:01, Daniel Stirnimann <daniel.stirnimann at switch.ch>
> > wrote:
> > 
> > > >     Now, the only strange result left is if I look up the name using my
> > > >     local resolver which returns 10800.
> > > >
> > > > Your local recursive server will give you the cache TTL, which is the
> > > > amount of time remaining on the TTL, not the TTLs original value.
> > >
> > > I don't think this is the case. I get the same result if I flush the cache.
> > >
> > 
> > Is it possible your recursive server implements a max TTL configuration
> > value that is set to 10800?
> > 
> > I'm curious what recursive server you're using, if the TTL it reports
> > doesn't decrement as time passes.
> 
> Probably BIND, where the default 'max-ncache-ttl' setting is 10800. The
> Unbound equivalent is 'cache-max-negative-ttl' and its default is 3600.

Also, there was a nice presentation of this topic in Amsterdam.

https://indico.dns-oarc.net/event/21/contribution/4/material/slides/0.pdf

-- 
Robert Edmonds