UNIX and the Internet

1. 2-3 sentences, define each of the following terms as they relate to UNIX and the Internet:

a) Port
b) Client
c) IP address
d) Server
e) Protocol
f) Nslookup
g) Usenet
h) Traceroute
i) lynx
j) ftp

2. What is the importance and/or use of the program Telnet?

3. My co-worker Mark and I both regularly use our mainframe UNIX system. I've fingered him, and know that he's logged on. While I do not want to have a conversation with him, instant messenger with him, or send him an email, I would like to send him a short message to meet for a break at 2:00. From within the UNIX system, and without using the mail command, is there a utility that would allow me to do this? If so, how does it work?