One of the keys to resolving network issues quickly is to know what is on your network. Recently I was at a client site and the "S" word was being thrown around. That "S" word is should. "This should be connected here" or "The address of that device should be".
It this case, I had my NetAlly Etherscope nXG with me. By plugging it into the network and running a quick discovery, I was able to determine exactly what was plugged into the network and where it was connected. This took all of the guess work out of determining addresses and connectivity.
We were able to track down the switch port, correct the settings and validate the issue was resolved. In addition, I was able to upload the discovery to Link Live. This snapshot of the network is now available for future troubleshooting. It also comes in handy when someone says nothing changed on the network, when a problem has occurred. I can compare the snapshot with the current discovery and see exactly what changed!
Regardless of the tools you use, know your network. Stop using the "S" word and be definitive in your statements.