RFC 1918/3330/5735

[Leandro]

Hello guys.
I was writting the reverse zone definitions you recommended some weeks ago.
What I understood is that RFC 1918/3330/5735 defines the reserved ips 
for internal or experimental use. They can not be routed outside a 
private network.
It means that my dns cache server should not send those queries to root 
servers.
I declarer all those ips on a single reverse zone (just showing 3 zones):

zone "10.in-addr.arpa" IN{        //for 10.X.X.X
     type master;
     file "named.loopback";
     allow-update { none; };
};

zone "16.172.in-addr.arpa" IN{        //for 172.16.X.X
     type master;
     file "named.loopback";
     allow-update { none; };
};
zone "168.192.in-addr.arpa" IN{        // for 192.168.X.X
     type master;
     file "named.loopback";
     allow-update { none; };
};

and use the " named.loopback" file for all of them wich contains:
$TTL 1D
@    IN SOA    @ rname.invalid. (
                     0    ; serial
                     1D    ; refresh
                     1H    ; retry
                     1W    ; expire
                     3H )    ; minimum
     NS    @
     A    127.0.0.1
     AAAA    ::1
     PTR    localhost.

Im not shure how to declare a  RR to point to "nowhere". My workaround 
is working but I wonder if it is good practice.
Any suggestion is wellcome.
Thanks in advance ,
Leandro.