[DNSOP] draft-ietf-dnsop-zoneversion doesn't handle this situation

["John R. Levine" <[e-mail]>]

It currently says:

  A name server MAY include more than one ZONEVERSION option in the
  response if it supports multiple TYPEs. A name server MUST NOT include
  more than one ZONEVERSION option for a given TYPE.

Here is a real life example from my server sdn.iecc.com:

;; QUESTION SECTION:
;com.ws.sp.am.			IN	A

;; ANSWER SECTION:
ws.sp.am.		300	IN	DNAME	whois.services.net.
com.ws.sp.am.		300	IN	CNAME	com.whois.services.net.
com.whois.services.net.	300	IN	CNAME	whois.verisign-grs.com.

The query is for com.ws.sp.am, which is a DNAME in ws.sp.am which points
to a name in whois.services.net which is another CNAME.  Both zones are
on the same server, so it answers for both.

In this case you can tell that the first CNAME is invented from the
DNAME, but imagine if the first CNAME was actually in the ws.sp.am
zone. If you only get one CNAME version response, which one is it, and
how can the client tell which one it refers to? Or if you really mean
that there should be one response per zone rather than one per RRTYPE,
how do you match them up?

R's,
John