This document is a must read for any serious network admin and i do dare to say also for a DBA.

.Net developers are welcome to read it since it is usefull.

A few excerpts:

(1) It Has To Work.

(3) With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it  

      could be dangerous sitting under them as they fly overhead.

(4) Some things in life can never be fully appreciated nor understood unless experienced firsthand. Some things in networking can never be fully

      understood by someone who neither builds commercial networking equipment nor runs an operational network.

(5) It is always possible to aglutenate multiple separate problems into a single complex interdependent solution. In most cases this is a bad idea.

(10) One size never fits all.

(12) In protocol design, perfection has been reached not when there is nothing left to add, but when there is nothing left to take away.

Full document can be found here.