Reverse dns des not reach my IP

[Matthias Wimmer]

Hi Andy!

Andy Shellam schrieb:
> Can you explain further on this?
> I.e. what the ISP will have to put in their zone file and what the OP 
> would have to put in his zone file?

Reverse lookups for 84.45.66.158 and 84.45.66.159 are made on 
158.66.45.84.in-addr.arpa and 159.66.45.84.in-addr.arpa as you probably 
know. So what your provider has to do at least is to put two CNAME 
records for this:

158.66.45.84.in-addr.arpa	IN CNAME <something>
159.66.45.84.in-addr.arpa	IN CNAME <something>

> Also would it have to still be an "in-addr.arpa" zone, or could, for 
> example, the OP put a PTR record in his "mydomain.com" forward-zone?

Technically it can be in any zone, while I have only seen it yet in the 
in-addr.arpa zone. Resolving might be a bit faster if the CNAME 
destination is in the in-addr.arpa zone as well if now forward 
resolution is made on the record. (You will not have to traverse the DNS 
tree from the root again.)

> Can you give an example of what's needed on both sides?

What I have seen most of the time would be this setup:

On your providers server:
158.66.45.84.in-addr.arpa IN CNAME 158.158-159.66.45.84.in-addr.arpa.
159.66.45.84.in-addr.arpa IN CNAME 159.158-159.66.45.84.in-addr.arpa.
158-159.66.45.84.in-addr.arpa IN NS yourserver.example.com.

And on yourserver.example.com:
158-159.66.45.84.in-addr.arpa IN SOA <the typical stuff>
158-159.66.45.84.in-addr.arpa IN NS yourserver.example.com.
158.158-159.66.45.84.in-addr.arpa IN PTR server1.example.com.
159.158-159.66.45.84.in-addr.arpa IN PTR server2.example.com.

This setup is resembling the guides in RFC 2317 that are suggested for 
Classless IN-ADDR.ARPA delegation.


Matthias