$TTL 86400
@ IN SOA ns1.tophk.net.  info@tophk.net. (
                2       ; Serial        ; Increment by one after every change
                3600    ; Refresh every hour
                900     ; Retry every 15 minutes
                3600000 ; Expire 1000 hours
                3600 )  ; Minimum 1 hour

                IN      NS      ns1.tophk.net.
                IN      NS      ns2.tophk.net.

1       600     IN      PTR     localhost.