$ORIGIN ???.???.172.in-addr.arpa.
$TTL 7200       ; 2 hours
@               IN      SOA             @     root.st??-c304.usv.ro. (
                        9001 ; serial
                        3600 ; refresh (1 hour)
                        1800 ; retry (30 minutes)
                        1209900 ; expire (2 weeks)
                        86400 ; default_ttl (1 day)
                        )

;serverele DNS
@       IN      NS      ns.st??-c304.usv.ro


;DE EXEMPLU:
???     IN      PTR     ns.st??-c304.usv.ro.
???     IN      PTR     mail.st??-c304.usv.ro.
???     IN      PTR     host1.st??-c304.usv.ro.