1. List five nonproprietary Internet applications and the application-layer protocols that they use.
2. What information is used by a process running on one host to identify a process running on another host?
3. List the four broad classes of services that a transport protocol can provide. For each of the service classes, indicate if either UDP or TCP (or both) pro-vides such a service.
4. Why do HTTP, FTP, SMTP, and POP3 run on top of TCP rather than on UDP?
5. Skype uses P2P techniques for two important functions. What are they?
6. For the client-server application over TCP described in Section 2.7, why must the server program be executed before the client program? For the client-server application over UDP described in Section 2.8, why may the client program be executed before the server program?