RFC2317-style delegation, nothing beyond CNAME

[eric.benoit at gmail.com]

Hey all,

I'm trying to figure out what has recently gone wrong with my reverse
DNS. I've been at the receiving end of RFC2317-style delegation for a
number of years now, and up until recently everything has worked
flawlessly.

The problem seems to be in that the majority of the time, I'm only
getting the CNAME response, and that's it. Other times I get a "has no
PTR record" response. These results seem to be consistent from around
the globe.

Example:

$ host 66.11.175.130
130.175.11.66.in-addr.arpa is an alias for 130.128/30.175.11.66.in-
addr.arpa.

(and it stops there)

Note that it does seem to work eventually and sporadically, and this
is what I expect:

$ host 66.11.175.130
130.175.11.66.in-addr.arpa is an alias for 130.128/30.175.11.66.in-
addr.arpa.
130.128/30.175.11.66.in-addr.arpa domain name pointer
paradise.ecks.ca.

Here's what dig says (with some parts omitted for brevity):

$ dig -x 66.11.175.130 @ns1.igs.net +trace
(skipped.. usual header, root servers, arin, etc)

175.11.66.in-addr.arpa. 86400   IN      NS      dci.doncaster.on.ca.
175.11.66.in-addr.arpa. 86400   IN      NS      ns.istop.com.
;; Received 103 bytes from 192.26.92.32#53(henna.ARIN.NET) in 62 ms

130.175.11.66.in-addr.arpa. 86400 IN    CNAME
130.128/30.175.11.66.in-addr.arpa.
;; Received 91 bytes from 209.195.118.109#53(ns.istop.com) in 50 ms

.. and stops there. I don't even see queries against my DNS server
(based on its logs).

I can proceed manually, though:

$ host -t NS 128/30.175.11.66.in-addr.arpa.
128/30.175.11.66.in-addr.arpa name server ns.oddity.ca.

$ host -t PTR 130.128/30.175.11.66.in-addr.arpa ns.oddity.ca
(skip)
130.128/30.175.11.66.in-addr.arpa domain name pointer
paradise.ecks.ca.

The relevant part of named.conf is pretty basic:

zone "128/30.175.11.66.in-addr.arpa" {
        type master;
        file "/etc/namedb/db.66.11.175.128-30";
}

and the zone itself:

$TTL 2h
@       IN      SOA     ns.oddity.ca. dnsadm.oddity.ca. (
                        2008061502 2h 1h 2w 1h
)
        IN      NS      ns.oddity.ca.

128     IN      PTR     quandary.oddity.ca.
129     IN      PTR     grumpy.nanuq.ca.
130     IN      PTR     paradise.ecks.ca.
131     IN      PTR     paradise.ecks.ca.

Any ideas why it seems to fail where it does? At first I suspected it
was in part due to the update to BIND 9.3.5 (from 9.3.4-P1) as part of
FreeBSD 6.3-STABLE, but the last time reverse seemed to have worked
was just prior to that update. A temporary downgrade didn't seem to
provide any relief.

BTW, if anyone familiar with this (former) ISP is suggesting I switch
as of yesterday, I'm certainly considering it now.

Thanks