Dear Classmates,
It is about time to study Chapter 2 and do Homework #2. The homework assignment for
Chapter 2 is as follows.
This homework consists of three parts: #2A, #2B, and #2C. Total credit: 200 points.
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Homework #2A: Self-Assessment Quizzes: Chapter 2 MC (10 questions) and Chapter 2
T/F (10 questions); Credit: 40 points (2 points/each)
Visit the textbook website to access quizzes:
http://www.aw-bc.com/kurose_ross/
Due date: Submit your answers to mblcourse@gmail.com and to your email address as
a backup by 9 a.m., April 16 (Monday), 2012 (late submission: zero point).
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Homework #2B Review Questions and Problems (from Chapter 2, page 205)
R9, R18, R24, R28
P4, P7, P8, P10, P16, P22
Credit: 100 points (10 points/each)
Due date: by 9:50 a.m., April 16 (Monday), 2012 (turn in the homework to the classroom)
Late homework: 1. By 9 a.m., April 17 (Tuesday), 2012 (Throw the homework into my
office, EC 332A): 30% of total points deducted
2. After 9 a.m., April 17 (Monday), 2012: 100% of total points deducted
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Homework #2C: Wireshark Lab: HTTP
Credit: 60 points
Visit the textbook website: http://www.aw-bc.com/kurose_ross/ to get lab material.
Having gotten our feet wet with the Wireshark packet sniffer in the introductory lab (Lab 1),
we’re now ready to use Wireshark to investigate protocols in operation. In this lab, we’ll
explore several aspects of the HTTP protocol: the basic GET/response interaction, HTTP
message formats, retrieving large HTML files, retrieving HTML files with embedded
objects, and HTTP authentication and security. Before beginning these labs, you might
want to review Section 2.2 of the text.
Due date and late homework: Same as those for Homework #1B (staple 裝訂 HW #2B
and HW #2C together)
If you have any question, please let me know.
Peace and Joy,
Kuochen
R18:
Yes an organization’s mail server and Web server can have the same alias for a host
name. The MX record is used to map the mail server’s host name to its IP address.
R24:
The overlay network in a P2P file sharing system consists of the nodes participating in the
file sharing system and the logical links between the nodes. There is a logical link (an
“edge” in graph theory terms) from node A to node B if there is a semi-permanent TCP
connection between A and B. An overlay network does not include routers. With Gnutella,
when a node wants to join the Gnutella network, it first discovers (“out of band”) the IP
address of one or more nodes already in the network. It then sends join messages to
these nodes. When the node receives confirmations, it becomes a member of the of
Gnutella network. Nodes maintain their logical links with periodic refresh messages.
R28
With the UDP server, there is no welcoming socket, and all data from different clients
enters the server through this one socket. With the TCP server, there is a welcoming
socket, and each time a client initiates a connection to the server, a new socket is
created. Thus, to support n simultaneous connections, the server would need n+1
sockets.