These are four helpful links for anyone in the business of administering or engineering computer networks. Those documents seem simple but are very helpful indeed.
What are the different wireless network security methods?
http://windows.microsoft.com/en-us/windows-vista/what-are-the-different-wireless-network-security-methods
Cisco Router Configuration Tutorial (defunct, looking for new link)
http://www.joshgentry.com/cisco/cisco.htm
Routing Protocol Comparison (PDF file)
http://www.routeralley.com/ra/docs/routing_protocol_comparison.pdf
ASCII Table
http://www.asciitable.com
Yes, I keep forgetting these things all the time.