[dns-operations] Surprising behaviour by certain authoritative name servers

[Niall O'Reilly]

Hi.

I've had my attention drawn to some surprising behaviour by
certain authoritative name servers. I'm not sure how best
to categorize this behaviour, and wonder how some of you
might view it.

What's surprising is that an authoritative name server
shows both a decremented TTL value (as if it were answering
from cache) and the AA flag.

I'm not sure which of the following labels is the best fit
for this behaviour:

- normal and expected (but so far outside my experience),
- strange but harmless,
- downright wrong.

Thanks in advance to whomever is minded to reply.

Thanks especially to Mats Dufberg who, diligently
investigating what I had mistakenly guessed was a problem
in zonemaster, took time to identify, and make me aware of,
what was causing occasional trouble reports.

Niall
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