Assistance with reverse lookup zone

[Kirk]

Frank Pikelner wrote:
> 
> Every now and then we get a bounce on emails that are sent through one 
> of our mails servers located on 64.187.3.170. The bounce messages look 
> as follows and appear to indicate that our reverse zone is missing a 
> record, though the record is there and resolves through nslookup. The 
> ISP delegates a number of IP addresses from the zone back to us (16 IP 
> addresses). So my guess is that our zone file needs to be rewritten or 
> there may be something else I'm missing.
> 
> 
> <first_last at some_domain.com>: host mx.some_domain.com[xxx.xx.xx.xx] 
> said: 450 4.7.1 Client
>     host rejected: cannot find your hostname, [64.187.3.170] (in reply 
> to RCPT
>     TO command)
> 
> 
> Performing a manual reverse lookup correctly displays the correct name 
> for 170.3.187.64.in-addr.arpa. Our zone file looks as follows (other 
> records removed):
> 
> $ORIGIN .
> $TTL 86400      ; 1 day
> 3.187.64.in-addr.arpa   IN SOA  ns1.blue-dot.ca. dnsadmin.ns1.blue-dot.ca. (
>                                 2009011401 ; serial
>                                 1800       ; refresh (30 minutes)
>                                 900        ; retry (15 minutes)
>                                 604800     ; expire (1 week)
>                                 1800       ; minimum (30 minutes)
>                                 )
>                         NS      ns1.blue-dot.ca.
>                         NS      ns2.blue-dot.ca.
>                         NS      ns3.blue-dot.ca.
> $ORIGIN 3.187.64.in-addr.arpa.
> 170                     PTR     smtp3.netcraftcommunications.com.
> 
> 

Read up on RFC2317.  Your ISP has delegated the block to you via this 
method.

Also do a "dig +trace -x 64.187.3.170" to see the delegation.