reverse lookup for single address

[Tony Tung]

Hi,

I'm trying to get my name server on my server to answer reverse lookup.
That is, my server lives at 12.34.56.78 (address faked), but that is the
only address I have.  I want to be able to do this from a remote server:

nslookup 12.34.56.78 12.34.56.78

and get a correct resolution.  I've managed to do that much.  However, I
can no longer reverse-resolve other addresses in the same subnet from my
own server, i.e., I cannot reverse-map 12.34.56.80.

Can someone give me some tips?  This is what I have in my named.conf:

zone "56.34.12.in-addr.arpa" IN {
        type slave;
        file "master/pub.rev";
        masters {
            64.81.79.2;
            216.231.41.2;
        };
};

and in pub.rev:

$ORIGIN 56.34.12.in-addr.arpa.
$TTL    3600
@       IN      SOA
myserver.org. root.myserver.org.  (
                                20030406        ; Serial
                                3600    ; Refresh
                                900     ; Retry
                                3600000 ; Expire
                                3600 )  ; Minimum
        IN      NS      myserver.org.
78      IN      PTR     myserver.org.


Thanks!
Tony