Intriguing. I think there might be a temptation to take this idea one step
further and say that preference should be given to the *smallest* RRset
possible -- to reduce the degree of amplification. But that would be a mistake.
It would, for instance, discriminate IPv4 over IPv6 (since A records are
smaller than AAAA records) and certain services over others (SRV records are
larger than MX records are larger than A records). When the client doesn't get
the RRset it wants from the QTYPE=* query, it'll follow up with one or more
subsequent queries for the type(s) it cares about. Not very efficient, and the
end result is more "amplification" than was hoped for.
Ideally, the QTYPE=* responder should *learn* what is most *useful* to the
client, e.g. if the client usually follows up a QTYPE=* query with a QTYPE=MX
query, whenever it doesn't get MX as the chosen QTYPE of the response, then try
picking MX as a response to the QTYPE=* more often and see if the client is
happier, i.e. the number of followup queries goes down.
Alas, this level of adaptive behavior would require holding more per-client
state information in the server than is comfortable, and in any case, is
probably beyond the algorithmic capabilities of most DNS implementers...
- Kevin
-----Original Message-----
From: DNSOP [mailto:dnsop-boun...@ietf.org] On Behalf Of Tony Finch
Sent: Wednesday, March 25, 2015 5:57 PM
To: Evan Hunt
Cc: dnsop@ietf.org
Subject: Re: [DNSOP] another way to minimize ANY responses
> On 25 Mar 2015, at 20:50, Evan Hunt <e...@isc.org> wrote:
>
> Last night the dumb-idea fairy visited me as I was falling asleep, and
> suggested that another way to reduce the impact of ANY queries would
> be to pick *one* rrset and return just that.
Very nice :-)
Tony.
--
f.anthony.n.finch <d...@dotat.at> http://dotat.at
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