What is correct way to enable watchdog?

[Peter Steele]

>No, meaning, if a system is unresponsive for 300 seconds, action will be 
>taken. watchdogd will not prevent proper reboots, panics or power failures. 

Bad wording on my part. What you said is what I meant, and I assume the default action is to reboot the system? 

>Panic, or overheating. Check the dumpdev/dumpdir variables in rc.conf(5). 

We don't have dumpdev/dumpdir configured in rc.conf. I'll do that. What makes us suspicious is that we have been running this stress test on systems for months without any reboots. We then enable the 300 second watchdog and two systems spontaneously reboot. We've turned it off again and have restarted the stress test and so far no reboots. What we want to know is are these reboots occurring as a result of a watchdog reboot? Is any kind of system log created when the watchdog reboots a system?