in reply to Sarah Brown

I want to get to know the other 1.5 people!

For many, it's turned out to be easier than it looked. I've given TCP/IP courses at novice level (just enough for system administators to design and configure simple networks) and have noticed that once you get past how the shorthand notation works, those with a firm understanding of binary numbers have little trouble picking it up. People who don't understand why 256 doesn't go in an IPv4 address, or why 255.255.0.255 is not a valid network mask, also have a hard time learning IPv6.