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

[Mukund Sivaraman]

On Tue, Jan 07, 2020 at 12:20:01PM +0000, Niall O'Reilly wrote:
> 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.

These days, another kind of authoritative nameservice seems to have
arrived - the "reverse proxy" idea adapted to DNS. It may forward an
authoritative query upstream, cache the result and return an
authoritative answer counting down the TTL. We know this scheme well as
a forwarder during resolution, but it appears it's being used in
authoritative service too.