HELP: Reverse (PTR) lookup problems on domain name.

[Dan Herold]

We have experiencing a reverse lookup problem that is preventing our mail
server from delivering messages into particular domains which perform
reverse lookups on the address of the incoming mail server.

The problem (we suspect) stems from the fact that PTR queries on
"backweb.com" in addition to our mailserver "mail.backweb.com" is failing as
the following nslookup output demonstrates:

---
Default Server:  ns.backweb.com
Address:  209.167.90.10

> set qt=ptr
> backweb.com
Server:  ns.backweb.com
Address:  209.167.90.10

*** No domain name pointer (PTR) records available for backweb.com

> mail.backweb.com
Server:  ns.backweb.com
Address:  209.167.90.10

*** No domain name pointer (PTR) records available for mail.backweb.com
---

To clarify, our nameserver, ns.backweb.com only resolves forward DNS
lookups. All reverse lookups are handled by our ISP. If I attempt to perform
a reverse lookup on the IP address of "mail.backweb.com", 206.251.15.130,
the reply is handled properly:

---
> 206.251.15.130
Server:  ns.backweb.com
Address:  209.167.90.10

130.15.251.206.in-addr.arpa     name = mail.backweb.com
15.251.206.in-addr.arpa nameserver = name.roc.gblx.net
15.251.206.in-addr.arpa nameserver = name.phx.gblx.net
15.251.206.in-addr.arpa nameserver = name.iad.gblx.net
name.roc.gblx.net       internet address = 209.130.187.10
name.phx.gblx.net       internet address = 206.165.6.10
name.iad.gblx.net       internet address = 204.152.166.155
--

If anyone could provide me with some clues as to why reverse lookups on
"mail.backweb.com" and "backweb.com" are failing, I would most appreciative.
Are we missing a switch somewhere in BIND that enables this option?

The output I'm expecting when performing a PTR lookup on our backweb.com
domain is something similar to what I see if I perform the same query on
another domain, such as symantec.com:

> symantec.com
Server:  ns.backweb.com
Address:  209.167.90.10

symantec.com
        origin = ns1.symantec.com
        mail addr = domain.symantec.com
        serial = 2000031301
        refresh = 10800 (3 hours)
        retry   = 3600 (1 hour)
        expire  = 604800 (7 days)
        minimum ttl = 21600 (6 hours)

Again, thank you for any help anyone may be able to offer.
.drh

--
Dan Herold 
(drh at backweb.com)