How to debug in freebsd for all bad condition ?

[Lowell Gilbert]

"Basheer Faith" <maslak at ihlas.net.tr> writes:

> I use Freebsd6. My server sometimes reboots by itself. As the server rebooted I was not near it so I could not see on its display that  what the server wrote on display. 
> I want to see what the server gave an error. I could not find any error message in /var/log/message.
>
> How can I see concerning message?
> How can I active debug for this case?

Can you use a serial console?