The easest way to use Jenkinz to monitor cron job is use hudson_wrapper as show below:
1. Put hudson_wrapper.sh, from https://github.com/joemiller/hudson_wrapper, on each server, and update the /etc/crontab as below:
0 * * * * root /path/hudson_wrapper.sh Jenkinz_URL name command
2. The wrapper will create the job on the Jekniz server if it is not exist. So no Jenkiz configuration needed.