Good networking books for a beginner?

[James Long]

Somewhere I seem to recall having read an RFC which is a primer
on IP basics.  I remember especially liking the sections where
it described the the inter-relationships between the network mask,
the role that ARP plays, and the use of routing.

Darned if I can find such a thing now, though.  If anyone knows
what this was, I'd appreciate a pointer.  The plain-text, Courier-font
layout sticks in my head, which is what makes me think it was an
RFC that I saw, put I can't find it in a brief search on rfcs.org.

Jim