[dnsext] additional section processing for DNAME

[JINMEI Tatuya / 神明達哉 <[e-mail]>]

Hello,

I have one quick question about draft-ietf-dnsext-rfc2672bis-dname-21.
In its Section 3, the draft states:

   The DNAME RR causes type NS additional section processing.  This
   refers to action at step 6 of the server algorithm outlined in
   section 3.2.

And the "step 6" of section 3.2 is as follows:

   6.  Using local data only, attempt to add other RRs which may be
       useful to the additional section of the query.  Exit.

It's not clear to me what these mean...what's "type NS additional
section processing" (for DNAME RR) in the first place?  Does this
mean, for example, if an authoritative server of "example.com" has the
following DNAME RR:

dname.example.com. DNAME dname.example.org.

and it also happens to have authoritative AAAA or A RRset of
dname.example.org, then the server includes these AAAA/A RRsets in the
additional section?  This doesn't seem to make much sense to me, so I
guess "type NS additional section processing" should mean something
else, but I don't know what it is.

Could you clarify what it is, and what it is for?

Thanks,

(p.s. I spent some time of googling to find the answer myself, and I
noticed this change was introduced in rev 15 of this document around
when there was a WG last call.  So I suspect this is a response to a
last call comment, but I couldn't find the relevant discussion.
Hence this question, at the risk of asking something twice at the same
place)

---
JINMEI, Tatuya
Internet Systems Consortium, Inc.