Network Time Server IP addresses:

17.151.16.20
128.9.176.30
192.5.41.40

17.151.16.20 time.apple.com.
128.9.176.30 timekeeper.isi.edu
192.5.41.40 tick.usno.navy.mil

How To Make Network Cables

Learn how to make Straight Through
and Cross Over network Cables.

Network Loops

Network Loops can cause severe problems on your
local area network. Some good examples are here.

IP Subnets

Basic IP subnets.

Routed Network Design

Understanding Wide Area Network Design.
Why You Should Route?