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[_] DNS resolving oddity

Amias Channer me at amias.net
Mon Nov 6 09:35:19 GMT 2017

Hello _,


Low TTL is usually set when expecting to make a lot of changes, then you
crank it back up again when settled

Cheers
Amias

On 6 Nov 2017 09:12, "Craig Francis" <craig at craigfrancis.co.uk> wrote:

> Thanks for confirming Oliver,
>
> I’m trying to help the company who (not surprisingly) had DNS issues last
> week, and the setup seems odd (the 20s TTL seems wrong to me as well).
>
> This was just the first time I’ve seen a setup where you could get another
> Authority response when asking for an A record (i.e. after doing the NS
> lookups, and being told who should be the authority for that domain).
>
> And I’m running OSX as well, so not sure why I was needing the +noedns
> flag.
>
> Craig
>
>
>
> > On 5 Nov 2017, at 10:59 pm, Oliver Humpage <oliver at watershed.co.uk>
> wrote:
> >
> >
> >> On 5 Nov 2017, at 17:45, Craig Francis <craig at craigfrancis.co.uk>
> wrote:
> >>
> >> We finally get the answer, but this seems a bit weird/broken to me...
> yet somehow it works (for all?).
> >
> > I guess your concern is that a DNS server that should be authoritative
> for the domain isn’t returning an answer.
> >
> > However, what it is returning (an Authority section) is exactly what
> both the root and .com DNS servers returned. Therefore the client will
> simply carry on following the chain and ask one of the servers in the
> authority section, which as you noted works fine (on OS X I didn’t need the
> +noedns flag).
> >
> > So it’s slightly odd, but it’s all within spec. Of more concern is the
> 20s TTL, which is insanely low. Whatever you’re doing that requires that
> low a TTL, do it another way, cos that’s not really how DNS is meant to
> work :)
> >
> > Oliver.
> >
> > --
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