janharders - 11:54 am on Aug 11, 2008 (gmt 0)
looking at the log-files you should at least be able to determine, _when_ apache went down (when did the logs stop showing requests?). what exactly happend won't necessarily be in the apache-log (maybe you get some hints from the error-log), but in other system-logs.
since the engineer said, he "rebooted" (aka restarted) apache, that sounds like apache was still running but not taking any requests. wether you find a reason or not, I'd set up a monitoring script to check for outages (like, make a request every 5 minutes, log it's status and how long the response took) and if it happens again, you'll have to do further investigation, preferably with someone from your host.