$ORIGIN .
$TTL 300	; 5 minutes
12.11.10.in-addr.arpa	IN SOA	dns.seminar. trainer.seminar. (
				43         ; serial
				300        ; refresh (5 minutes)
				300        ; retry (5 minutes)
				604800     ; expire (1 week)
				86400      ; minimum (1 day)
				)
			NS	trainer.seminarnet.
$ORIGIN 12.11.10.in-addr.arpa.
1			PTR	trainer.seminarnet.
$TTL 1800	; 30 minutes
100			PTR	T530-2.seminarnet.