Reverse Delegation

[ArtF1]

I recently changed ISPs to SBC and they were fast and curtious and not the least bit helpful. They performed a reverse delegation of our IP block but I find that some email servers performing reverse lookups, will not accept messages from our domain. (We house our own email.)

Our NS is held by our webhost and I can add mx, cname and A records all day long. But I need to add a PTR record in a reverse lookup zone. Are there any workarounds or should I hoist anchor and find another host for my NS and website?

 

[jyorgey]

First question is - what how large is the reverse address block your ISP has delegated to you? If it has less hosts than a class C network(254) you will have to find out how your ISP has configured the reverse space. Your ISP will have to configure all the IP addresses in your reverse address space with CNAMES pointing to the the delegated space.
1.1.168.192.in-addr.arpa. IN CNAME 1.0-63.1.168.192.in-addr.arpa.
2.1.168.192.in-addr.arpa. IN CNAME 2.0-63.1.168.192.in-addr.arpa.

Your ISP will also have NS records for this delegated zone (0-63.1.168.192.in-addr.arpa) that should look like the following:
0-63.1.168.192.in-addr.arpa. IN NS ns1.your.server.com

You will then have to add PTR records in your db files that match the CNAME records your ISP has for your reverse block.
1.0-63.1.168.192.in-addr.arpa. IN PTR host.your.domain.
2.0-63.1.168.192.in-addr.arpa. IN PTR host2.your.domain.

The example above is assuming an address space of 192.168.1.0/27.

You can do an nslookup and set q=soa to see if your ISP has your block delegated to your name servers.