$ORIGIN .
$TTL 86400	; 1 day
100.15.10.in-addr.arpa	IN SOA	ns1.example.com. hostmaster.example.com. (
				2002022406 ; serial
				10800      ; refresh (3 hours)
				15         ; retry (15 seconds)
				604800     ; expire (1 week)
				10800      ; minimum (3 hours)
				)
$TTL 600	; 10 minutes
			NS	ns1.example.com.
$ORIGIN 100.15.10.in-addr.arpa.
50			PTR	user1-lt1.dhcp.site1.example.com.
$TTL 300	; 5 minutes
55			PTR	betaclean-lt1.dhcp.site1.example.com.