I came across this reading up on TCP/IP and thought it pretty much summed up setting up a TCP/IP network.
"These were devised by that seer and prophet, Murphy. Murphy states unequivocally:

1. If anything can go wrong, it will.
2. If there is a possibility of several things going wrong, the one that will cause the most damage will.
a. Corollary: If their is a worse time for something to go wrong, it will happen then.
3. If anything just cannot go wrong, it will anyway.
4. If you percieve that there are four possible ways in which something can go wrong, and you circumvent these, then a fifth way, unprepared for, will promptly develop.
5. Left to themselves, things tend to go from bad to worse.
6. If everything seems to be going well, you have obviously overlooked something.
7. Nature always sides with the hidden flaw.
8. Murphy was an optimist.