Classless PTR query issue

[Justin T Pryzby]

On Tue, May 07, 2013 at 09:52:16AM -0700, Michael Varre wrote:
> Thanks Justin, I've been testing with dig and that's how I got the failed results posted previously. My digs lead me to believe their zones are named the same as mine, with -'s instead of /'s. 
> 
> dig -x 1.1.1.90 +trace
> ----snipped----
> ;; Received 180 bytes from 199.253.183.183#53(b.in-addr-servers.arpa) in 89 ms
> 
> 1.1.1.in-addr.arpa. 86400  IN      NS      NS1.myisp.COM.
> 1.1.1.in-addr.arpa. 86400  IN      NS      NS2.myisp.COM.
> ;; Received 89 bytes from 199.180.180.63#53(r.arin.net) in 55 ms
> 
> 90.1.1.1.in-addr.arpa. 3600 IN     NS      dns1.myns.com.
> ;; Received 75 bytes from 13.13.13.13#53(NS1.myisp.COM) in 84 ms
> 
> ;; Received 44 bytes from 1.1.1.90#53(dns1.myns.com) in 80 ms
> <end>
> 
> I've requested they confirm their setup, but I don't know how forthcoming they'll be.

I don't see any "-" (or "/") in your dig output, which indicates that
the ISP delegation isn't using RFC2317-style delegation with CNAMES.

It appears they may have manually added NS records for each of 64 IPs.
That's messy and inelegant for them, and doesn't work right either.
The ISP is responding with NS for 90.1.1.1, which means that the next
query must ask a quesion *below* that: something.90.1.1.1.  That's why
a CNAME is needed, with an additional, "artificial" subzone, allowing
proper delegation.  Otherwise, it's a so-called "horizontal" referal.

In the past, when I've requested RFC2317/sub-24 delegation of rev dns,
I've included/suggested BIND syntax (but it's still sometimes taken
multiple attempts to be correctly implemented).

$ORIGIN 196.185.205.in-addr.arpa.
32-47 NS ns.norchemlab.com.
32-47 NS ns1.norchemlab.com.
$GENERATE 32-47 $ CNAME $.32-47

Justin