te time repeating steps that were ineffectual. Find Out What Changed Outages do not happen without cause. Even if there has not been an obvious device failure, if everything has been working-and now it's not-something has changed. In some environments, people will confess, and in others, they won't. Either way, the Troubleshooting first question you should ask is, "What changed?" If something changed just before the outage, there is a good chance that the change is related to the outage. Figure out if you can reverse the change, but make sure you know before you act what the impact of your reversal will be. Outages can be caused by seemingly unrelated changes. When I used to work with mainframes, I witnessed some pretty strange outage scenarios. One customer com- plained that his mainframe was crashing every night between midnight and 1:00 a.m. There were no obvious causes for the crashes, but they happened every weeknight, and had only started about a month earlier. While the customer was very helpful and understanding, backups were not completing because of the crashes, and this was causing problems. Finally, we sent someone out to the site to literally sit with the system for a week to see what was going on. The person we sent to babysit the system noticed a police officer parked in the com- pany's parking lot every weeknight at around midnight. When the officer left the parking lot, he called the dispatcher on his radio. As soon as the officer pushed the button on his radio microphone, the system crashed. We determined that the system administrator had disconnected a group of terminals from the mainframe about a month prior to our visit. He had removed the terminals, but had left the serial cables connected to the mainframe. These cables were acting as antennas. When the police officer keyed up his radio, the serial cables received the signal, and the resulting electrical impulses entering the mainframe caused it to crash. If you can't figure out the cause of a problem or outage, look for any changes, no matt