$TTL	60000
@		IN	SOA	50.40.30.in-addr.arpa.	nobody.nowhere. (
			1 ; serial
			28 ; refresh
			14 ; retry
			3600000 ; expire
			0 ; negative cache ttl
			)
@				IN	NS	253.50.40.30.in-addr.arpa.
253.50.40.30.in-addr.arpa.	IN	A	30.40.50.253

253	PTR	dnscom.com.