buggy nameservers resolve x.y.z CNAME a.b.c but not x.y.z. CNAME w.y.z

[Mark Andrews]

> I've had problems for a couple of years now with certain providers not
> being able to resolve www.jcomeau.com which WAS an alias to
> unixshell.jcomeau.com (I've now changed it to an A record). I've been
> doing some testing today, and it seems these DNS daemons balk on doing
> recursive queries to the same domain.
> 
> I now got:
> 
> test.jcomeau.com. 28800 IN CNAME www.jcomeau.com.
> test2.jcomeau.com. 28800 IN CNAME cosf.unternet.net.
> 
> Both of these CNAME targets point to the same server, but the first one
> fails on Qwest's nameservers 206.81.128.1 and 206.80.192.1, and the
> second works. If you try it within the next 8 hours, though, you'll see
> cached records that confuse the issue somewhat.
> 
> Any of you who have xxx.domain.zzz CNAMEd to yyy.domain.zzz, and have
> people unable to reach your site, you may be a victim of such buggy
> nameservers. At least I *THINK* it's a bug... if anyone can point out
> something I overlooked, please do. Thanks -- jc

	Well the NS RRset is incorrect in this reply.

; <<>> DiG 9.3.2 <<>> test.jcomeau.com @ns1.domaindiscount24.net +norec
; (1 server found)
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27441
;; flags: qr aa; QUERY: 1, ANSWER: 2, AUTHORITY: 3, ADDITIONAL: 0

;; QUESTION SECTION:
;test.jcomeau.com.		IN	A

;; ANSWER SECTION:
test.jcomeau.com.	28800	IN	CNAME	www.jcomeau.com.
www.jcomeau.com.	28800	IN	A	207.210.74.124

;; AUTHORITY SECTION:
test.jcomeau.com.	28800	IN	NS	ns1.domaindiscount24.net.
test.jcomeau.com.	28800	IN	NS	ns2.domaindiscount24.net.
test.jcomeau.com.	28800	IN	NS	ns3.domaindiscount24.net.

;; Query time: 102 msec
;; SERVER: 81.3.43.97#53(81.3.43.97)
;; WHEN: Tue Jul 11 05:01:20 2006
;; MSG SIZE  rcvd: 142

--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org