Revealed! Secrets behind IT magic tricks

When you're good, you can troubleshoot anything -- most of the time. Here are a few riddles and their solutions

Some IT folks have the magic touch when it comes to both consumer and enterprise computing gear. The same digits that might circumvent a bad situation by feverishly freehanding code into a switch to account for an unforeseen failure can also deftly cure an ailing smartphone.

This ability isn't without its drawbacks. For one thing, it can inspire jealousy and frustration when a seemingly insurmountable problem is spirited away in just a few seconds by someone with the touch. I suppose beating your head against a door for a few days only to have someone pull the handle instead could do that to someone.

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But as any magician knows, these tricks aren't magic at all -- you just need inside knowledge and a little practice. For those of you who aspire to wizard status, here's a couple real-world encounters of ghosts in the system.

Home router chaosThis situation usually occurs when someone is at home, connecting via a cable or DSL router. They've had a power outage or brief hiccup and possibly even an inadvertent connection to a neighbor's access point. After much gnashing of teeth, the router is power cycled, but that appears to have worsened the problem. After a period of utter dismay and forsaking all gods, the user finally reboots or power cycles everything in the area, and it all starts working again.

What's actually happened here is a series of DHCP address collisions. The router in use is of sufficiently poor design that it does not maintain DHCP lease tables across reboots, and it extends that deficiency with the lack of ICMP checking before handing out new addresses. Thus, when it powers back up, it dispenses addresses to anything that asks, regardless of whether that IP is already in use. Chaos ensues; some OSes figure out there's a duplicate IP, so they request another. This then breaks a running app and poof -- the TiVo in the back room won't connect to anything, and the wife or husband sitting on the couch is thrown off the network. Anarchy!

The remedy for this is fairly simple: Buy a better router. It's not terribly hard to do.