Subject: Re: summary/conclusion of discussion on mdns-00

From: Robert Elz <[email-masked]>
Date: Sun, 22 Jul 2001 06:18:46 -0700

Date:        Wed, 16 May 2001 23:49:40 +0900
    From:        Jun-ichiro itojun Hagino <[email-masked]>
    Message-ID:  <[email-masked]>

  | >> [9] Change text: 'A gratuitous name resolution query SHOULD be done 
  | >>     to check for a name conflict.  This is done by having the resolver
  | >>     send a multicast query for a SOA type query for its own name (i.e.
  | >>     for the name it is authoritative for.' 
  | >>     s/SHOULD/MAY/
  | >>     s/SOA/A/
  | >Again, I think that name conflicts are a problem and caution is
  | >advised. Recommend against the change.
  | 
  | 	i strongly object against s/SOA/A/ change.  we can't assume that every
  | 	device has an IPv4 address (think of IPv6 only devices).

Yes, but SOA is wrong too - since servers only send positive, non-empty
replies, the changes of an SOA query eliciting a reply are pretty small
(only if the name chosen happens to be the same as that of a separate zone,
they're the only things that have SOA records).

Why is an ANY query not done?   What does it matter what kind of data
exists - the point is to discover if the name exists, right?   That's
one of the rare cases where an ANY query actually makes sense (what's
more, it doesn't matter if all of the data can't be returned, or even
if a truncated answer is returned - if any data is returned the answer
that is desired is obtained).

The original text seems to be based upon a misunderstanding of the role
of SOA, and changing from using that is definitely correct.   But as you
point out, changing to A is not the answer - that is perhaps more likely
to exist than an SOA, but not guaranteed.  IN fact, nothing is guaranteed.
That's why ANY should work here - no-one cares what type the data is, just
that data exist - that is, that the name exists.

kre

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