[CentOS] System Rebooted by 2.6.18-8.1.8.el5

> This looks like a normal shutdown command was issued from somewhere,
> IMO. I would check the other log files under /var/log and its sub-
> directories for entries around this time. Especially secure.log*. Also,
> I don't know your configuration, but is there a cron or at entry that
> has a scheduled reboot?
>
>   

also check last log to see who was logged in