• Özyeğin University

• CS 447

CS 447 – Computer Networks Homework 3

1. What are the layers of the internet protocol stack? Give an example protocol used at

each layer.

2. Give four advantages of UDP over TCP.

3. Consider a web browser running on a machine with a high bandwidth Internet

connection, downloading an HTML document with ten embedded images where

each file (the HTML file and the 10 image files) is stored on a different web server, all

distant to the browser’s machine. Would you expect the time to completely display

this page be shorter under HTTP 1.1 compared with HTTP 1.0? Why or why not?

4. Briefly explain:

a) The difference between a “computer virus” and a “computer worm”?

b) Four reasons for having some parts of a network application to run in the

network core?

c) Three services that are not provided by the current Internet Transport Layer?

d) Can an HTTP server create a “session” in which every HTTP request is

associated with a session specific information such as the user’s identification?

5. At a public place offering free WiFi service, the wireless access point (AP) and the

wireless end devices connected to them use Layer-2 encryption to protect traffic

between them from packet sniffers. May the users still need encryption at Layer 4,

Layer 5, or both?