Ubuntu Servers :: Sudo Contrab Script To Ping Ebox

I have a DHCP server that I only mildly trust, but its nice because it is an eBox server (I use it for DNS, DHCP, and smtp relay for my internals). I want it to issue all addresses (simply because I like the way it displays its leases in the WebUI's dashboard), but I want a fail-safe too. I have another server that is strictly an Ubuntu Hardy server (I use it for openVPN and nothing else) so I would like it as my backup dhcp server. I figure I'll install all the dhcp stuff on it and just stop the service (to include a sudo crontab @reboot script to stop it when rebooted).

And simple use a sudo crontab script to ping the eBox every 5 minutes to make sure its live, and if not then start the dhcp server. My questions: If I put the entry in my sudo crontab will the script execute even if no session is currently running (its obviously a server so won't have anyone logged in except for administration)? Also since it is in the root crontab it will be able to start the init.d service without having to sudo it right (IE the script only needs to say "/etc/init.d/dhcp3-server start" not "sudo /etc/init.d/dhcp3-server start")?