$TTL 3600       ;

@     IN      SOA     example.org. root.example.org (

      20060204        ; Serial

      3600            ; Refresh

      900             ; Retry

      3600000         ; Expire

      3600            ; Minimum

      )

@     IN      NS localhost.

50    IN      PTR ns01.example.org.

60    IN      PTR ns02.example.org.

70    IN      PTR ns03.example.org.

12    IN      PTR test.example.org.