[avahi] PTR query responses

Christiano F. Haesbaert haesbaert at haesbaert.org
Mon Mar 12 09:12:04 PDT 2012

On 12 March 2012 13:08, Markus Rathgeb <maggu2810 at googlemail.com> wrote:
> Hello!
> I have here multiple machines with the same setup.
> Normally if a multicast question for a PTR "_srv._proto.local" is
> made, the machines reply with a multicast response containing four
> records, the types PTR, TXT, SRV, A.
> This morning I see (wireshark) a machine that reply contains only the
> PTR record -- missing the TXT, SRV and A type.
> If a multicast question for the A record of the machine's name is
> requested, the machine answered with a multicast respone given the A
> record.
> After a restart of the avahi daemon of this machine, the machine's
> reply to the PTR question contains all four records (PTR, TXT, SRV, A)
> again.
> What's going on?
> Could someone explain me, how I could run in that situation and
> whether it is correct or not (why)?
> Thanks in advance,
> Markus

There is a feature called something like "Known Answer Suppression",
the querierer includes the known answers in the query packet, under
the AN section, so the the one getting queried won't include the known
answers in the reply.

Not sure if I made myself clear, try using avahi-browse, if the
service ain't there, it's wrong.

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