reverse zone file network portion

[ChrisC]

Hello

I am setting up a reverse zone file for a network portion give to us
by our isp.

I have 213.161.84.64/27, but for some reason the reverse zone only
works if I specify 84.161.213.in.addr.arpa but not
64/27.84.161.213.in.addr.arpa or 64-95.84.161.213.in.addr.arpa (I take
it these mean the same). Is this because the isp has to delegate
something ?

It only works with the zone definition below (I can resolve
213.161.84.92 on the dns server) but I believe I should only define my
own network portion.


My /etc/named.conf is

zone "84.161.213.in-addr.arpa" in {
        type master;
        file "named.rev";
        allow-query { "any"; };

And my named.rev is

$TTL 86400 
@       IN      SOA     ns2.issolutions.co.uk.
postmaster.ns2.issolutions.co.uk. (
        2001031900      ; Serial Number CCYYMMDDNN 
        43200           ; Retry
        3600            ; Refresh
        604800          ; Expire
        86400 )         ; Ttl

        IN      NS      ns2.issolutions.co.uk.
92      IN      PTR     ns2.issolutions.co.uk.


Could someone tell me what I need to do, or if I have an error in my
named files.
Thankyou.