$TTL	86400 ; 24 hours could have been written as 24h or 1d
$ORIGIN 64/1.0.168.192.IN-ADDR.ARPA.
@  1D  IN	 SOA ns1.example.com.	mymail.example.com. (
			      2002022401 ; serial
			      3H ; refresh
			      15 ; retry
			      1w ; expire
			      3h ; minimum
			     )
			
 IN      NS      ns1.yournameserver.com.
 IN      NS      ns2.yournameserver.com.
							
; server host definitions
1      IN  PTR    ns1.example.com.
2      IN  PTR    www.example.com.            
; non server domain hosts
3      IN  PTR    bill.example.com.  
4      IN  PTR    fred.example.com.