$TTL 0
$ORIGIN 31.172.in-addr.arpa.

@                       IN  SOA  (
                                   ns.example.
                                   hostmaster.nic.example.
                                   2023040400
                                   86400
                                   14400
                                   3600000
                                   3600
                                 )

                            NS   ns.example.

$ORIGIN 0.31.172.in-addr.arpa.

53                          PTR  ns.example.

$ORIGIN 10.31.172.in-addr.arpa.

1                           PTR  mx.expediteur.example.

$ORIGIN 20.31.172.in-addr.arpa.

1                           PTR  mx.destinataire.example.

$ORIGIN 30.31.172.in-addr.arpa.

1                           PTR  mx.attaquant.example.