named.conf.local:

//
// Add local zone definitions here.

    zone "casanostra" {
        type master;
        file "/etc/bind/db.casanostra";
    };

    zone "1.168.192.in-addr.arpa" {
        type master;
        file "/etc/bind/db.1.168.192";
    };


db.1.168.192:
;
; BIND reverse data file for local loopback interface
;
$TTL    604800
@   IN  SOA casanostra. root.localhost. (
             2007072807     ; Serial
             604800     ; Refresh
              86400     ; Retry
            2419200     ; Expire
             604800 )   ; Negative Cache TTL
;
@   IN  NS  localhost.

100   IN  PTR bob.casanostra.
101   IN  PTR bianca.casanostra.