$ORIGIN 0.168.192.IN-ADDR.ARPA.
$TTL 3600
@	IN	SOA	NS1.NAMESERVER.NET.	HOSTMASTER.MYDOMAIN.COM.	(
			1406291485	 ;serial
			3600	 ;refresh
			600	 ;retry
			604800	 ;expire
			86400	 ;minimum ttl
)

@	NS	NS1.NAMESERVER.NET.
@	NS	NS2.NAMESERVER.NET.

1	PTR	HOST1.MYDOMAIN.COM.
2	PTR	HOST2.MYDOMAIN.COM.

$ORIGIN 30.168.192.in-addr.arpa.
3	PTR	HOST3.MYDOMAIN.COM.
4	PTR	HOST4.MYDOMAIN.COM.
	PTR HOST5.MYDOMAIN.COM.
	IN PTR HOST6.MYDOMAIN.COM.

$ORIGIN 168.192.in-addr.arpa.
10.3	PTR	HOST3.MYDOMAIN.COM.
10.4	PTR	HOST4.MYDOMAIN.COM.