[...]
# updating the bind slaves every 15 minutes
# m	h	dom	mon	dow	user	command
14	*	*	*	*	root	perl /root/mydns_to_slave.pl
29	*	*	*	*	root	perl /root/mydns_to_slave.pl
44	*	*	*	*	root	perl /root/mydns_to_slave.pl
59	*	*	*	*	root	perl /root/mydns_to_slave.pl