Hello Mark,

Thank you for your swift and accurate response.

On Oct 26, 2012, at 15:12 , Mark Andrews wrote:

> 
> You asked a ANY query.  ANY and CNAME have different processing rules.
> The query is NOT restarted with the target of the CNAME.  See RFC 1034.
> 
>> NSD returns the same minus the ra flag.
>> 
>> PowerDNS, however, returns:
> 
> You asked a different question (A != ANY).  If you want to compare
> answers you need to ask IDENTICAL questions.

My mistake.

NSD:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34556
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; QUESTION SECTION:
;nxd.example.com.               IN      A

;; ANSWER SECTION:
nxd.example.com.        120     IN      CNAME   nxdomain.example.com.


BIND, PowerDNS (same except for ra flag)

;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 4382
;; flags: qr aa ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 1
;; QUESTION SECTION:
;nxd.example.com.               IN      A

;; ANSWER SECTION:
nxd.example.com.        120     IN      CNAME   nxdomain.example.com.

;; AUTHORITY SECTION:
example.com.            86400   IN      SOA     ns1.example.com. 
ahu.example.com. 2000081501 28800 7200 604800 86400


To be complete: 

- for the A query, BIND and PowerDNS return NXDOMAIN+SOA, NSD returns NOERROR.
- for the ANY query, NSD and BIND return NOERROR, PowerDNS returns
  NXDOMAIN+SOA.

Then, as far as I can tell, BIND and PowerDNS do the right thing for the A
query. NSD and BIND do the right thing for the ANY query, going from Mark's
interpretation of the RFCs.

However, 2308 and 6604 totally ignore the ANY exception to following CNAME
chains, and one might argue that thus, 2308 and 6604 still mean that QNAME is
the end of the CNAME chain in the response, and the RCODE thus should be
NXDOMAIN. I think this argument could go either way.

Unless conflicting opinions come in, I will fix PowerDNS to do the right thing
for ANY, and will report the A query issue to the NSD developers.

Kind regards,
-- 
Peter van Dijk
Netherlabs Computer Consulting BV - http://www.netherlabs.nl/

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