IBM Redbooks might be worth a look.
These are freely downloadable PDF`s on a wide variety of computer technologies.
A search on "networking" gave 463 hits, the start page is click here and a sample search result is click here
I do admit they are generally very technical, this one click here on TCP/IP protocols is a 7.7MB download and has 980 pages (yes I am sad enough to have read it <sigh>), so they may be far more complicated than you need, however they are free so you have nothing to lose.
Other than that try googling for articles relating to the particular area you want infomation on, such as using the Ping command.
Although there are differences in its usage on Windows, MAN pages available for *nix systems may be helpfull.