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[_] DNS resolving oddity

Oliver Humpage oliver at
Mon Nov 6 09:31:54 GMT 2017

> On 6 Nov 2017, at 09:11, Craig Francis <craig at> wrote:
> 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).

I’d say it's almost certainly the TTL.

> 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).

But you’re not being told the authority for that domain as such: you’re just being told the next link in the chain. Just because *normally* you get an answer at that point doesn’t mean it’s wrong to carry on the chain instead. All it means is that, with a 20s TTL, clients are having to do an extra hop to get to the answer. Every 20 seconds.