computer name on a LAN

[Michael Klinosky]

I have a 4-port router/dsl modem, and 4 machines connected. All of my 
linux units have F7. All of the machines have names (set in 
System>Admin>Network, in 'DNS'). E.g. d500.localdomain

I'm trying to learn rsync. However, I decided that learning a less 
complex program would ease the learning curve. So I'm working with rcp.

LQ has a small tutorial at   http://wiki.linuxquestions.org/wiki/Rcp
which states that I can give the computer name. However, it doesn't work:
[mpk at d500 documents]$ rcp info 5bw130:
5bw130: Unknown host

I also tried with its lan ip:
[mpk at d500 documents]$ rcp info 10.0.0.6:
10.0.0.6: No route to host

What's going on here?