Where should I start crond?

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http://askubuntu.com – On my Ubuntu server (LTS 12.04) I would like crond to be running every time I boot up. Where should I configure this? I took a look at service --status-all and saw that cron was there, but it was marked with a question mark. In general, where should a user add daemons that they want to be executed at boot? (HowTos)