particularly what is a mapped network(in this instance)
generally speaking a mapped network is one in which someone has taken the time to create a layout (visios is a great program for this, but time consuming) of all routers/switches/hubs on the network and some times each node if you are doing a small netowork. In my compnay we have a network map for every client we take on. so if anything ever breaks we can pull out a map and see where the problem is occuring if its a routing issue or a connectivity issue. Basicly its a quick refrence.

what they mean by "Note: Use of the user's IP address allows more targeting than with top-level domain alone (i.e .com)". what would be the point of identifying an ip address only by it's third level domain: .com, .org, etc. ? also, by domain do they mean like, if i have a domain name setup in a dns to point to my ip address they see that or what do they mean?
they mean that if they do a trace by just the url they cant get as much info as if they do it by IP. When you go by ip addres you can get a physical location or general location on where the server is. Most of the time to trace by domain name the tracer will resolve the ip and trace that. but ip is more specific anyhow, it can also give you info as to if they are running a netowkr off that IP or if it is just a box on the net etc. And yes, they mean if you have a domain set up by someone they trace that, they dont mean domain in the sense of saw a windows enviroment spit into domains.