LinuxPlanet: "Networks don't work without addresses: Whenever you are sending something, you need to specify where it should go and where it came from. To be an effective network engineer or administrator, you need to understand IP addresses backward and forward: you need to be able to think on your feet. If something breaks, likely as not some address assignment has been screwed up. And spotting the problem quickly is likely to be the difference between being the hero, or the guy who "takes a long time to fix the problem.""