strange response to the DS request

[Manabu Sonoda]

Hi

I know this is miss-configuration. but sharing.

I find the the strange response to the DS request.
That response answer type is CNAME.

This can happen if Child and Parent zone in same nameserver and
Parent zone does not have NS recode for Child zone and
Parent zone have CNAME recode with the same name as Child zone.

DS recode is authoritative data in the Parent zone.
but I think strange that response.


example:

dig @localhost www.example.jp SOA +norec
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 48
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

;; QUESTION SECTION:
;www.example.jp.			IN	SOA

;; ANSWER SECTION:
www.example.jp.		3600	IN	SOA	www.example.jp. dns-managers.example.jp. 1 3600 1800 3600 900


dig @localhost www.example.jp ds +norec

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.30.rc1.el6_6.2 <<>> @localhost www.example.jp ds +norec
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29723
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.example.jp.			IN	DS

;; ANSWER SECTION:
www.example.jp.		300	IN	CNAME	www.example.com.



-- 
Manabu Sonoda <manabu-s at iij.ad.jp>
Internet Initiative Japan Inc.