Reason for esxi reboot

I am trying to find out the reason for the esxi host reboot,  Can experts out there advice me where to look for it please?
i checked the vmksumary.log and noticed that bootstrap: host is powering off.
I want to know why it did reboot.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
loss of power ?

someone rebooted it ?

hardware failure ?

do you have persistent logging of the log files, or a syslog server, because ESXi does not keep the logs after a reboot ?

the location for all logs is /var/logs - but it might not be clear why the server rebooted.
sara2000Author Commented:
This is a dell PE server , i have checked idrac and server manager. Do not see anything on hardware related.
There was not power loss either.
How do i find whether someone rebooted via DCUI or vcenter?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Task and Events, and in the logs /var/logs

but it is sometimes unclear why a ESXi server reboots.
At this point you are in dark. Yu need to collect syslogs from both DRAC and ESXi outside of them. Probably they dont try to log death grasp right before shutting dowsn.
Could be windows admin at KVM pressing Ctrl=Alt-Del
sara2000Author Commented:
No one is accusing to this server other than me !! so no other admin  pressed any button to reboot, if it that case they will get warning from vsphere ?

And it is rebooted  at night time.
Ctrl-Alt-Del reboots it for good.
Collect syslog like with kiwi syslog, without that there is no telling what happened.
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