BIND PTR Question

[Ian Lists]

I know this isn't DNS/BIND list but I figured there might be someone here that could point me in the right direction.  I upgraded a Bind DNS server to RHEL5 and I am running into a strange issue with reverse lookups.  The server is only for my public name space, nothing internal.  When attempting to do a reverse lookup from the outside with /etc/resolv.conf pointing directly to the public IP of my DNS server I get the following response 106.100.100.100.in-addr.arpa has no PTR record.  (The 100.100.100 is just masking my real public space)  When I do the same query from a system internally with /etc/resolv.conf pointing directly to the private IP of DNS server, the query responds back correctly.  I don't have any "views" or ACL's applied that should cause this and regular lookups are working correctly.  
Here is the strange part, while watching the query on my DNS server with TCPDump, I noticed that some how the query from the outside is flipping every octet but the last one to my internal IP range.

For example from the Internet querying my DNS server
#host 100.100.100.15

This is what I see as the actual query on the DNS Server with TCPDump.
query: 15.120.16.172.in-addr.arpa IN PTR +

Thanks in advance.

Ian