Suppose this about the CentOS server and not any other service instances like httpd/nginx/named/postfix/etc?
If the former then how was the server shutdown (or powered off/failure)? There is a difference between shutdown and reboot. Latter does reboot the server after shutdown whilst shutdown just does what it says and does not automatically brings the server back online. And in case the server hard disk is encrypted the reboot will stop at the request of the encryption password, pending user input/interaction.
If the server went offline due to power failure or some other issue it would need to be rebooted manually.