$TTL 2d  ; 172800 seconds
$ORIGIN 56.168.192.IN-ADDR.ARPA.
@       IN        SOA        ns1.example.fake.  hostmaster.example.fake. (
                            201107111          ; serial number
                            3600               ; refresh, seconds
                            3600               ; retry, seconds
                            3600               ; expire, seconds
                            3600 )             ; minimum, seconds

                IN      NS      ns1.example.fake.
20              IN      PTR     server.example.fake.
40              IN      PTR     client1.example.fake.