$TTL    3600
53.52.51.in-addr.arpa.        IN SOA        ns2.example.net. admin.ns2.example.net. (
                              106          ; Serial
                              1h           ; Refresh [1h]
                              10m          ; Retry   [10m]
                              1d           ; Expire  [1d]
                              10m)         ; Negative Cache TTL [10m]

; Name Server
53.52.51.in-addr.arpa.        IN      NS       ns2.example.net.

; PTR Records
81.53.52.51.in-addr.arpa.     IN      PTR      ns2.example.net.