homework
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instructions: · The total number of points for each question is given in parenthesis. There are 100 points total. · Show all your work. Partial credit is possible for an incorrect answer, but only if you show some correct intermediate steps in obtaining the answer. · Provide screenshots for question 5. |
Question 1: Knowledge-based Questions. (32 points)
a) According to the course’s textbook, how many layers are included in the Internet (give their names too)? Give one example of application, or protocol, or device, that corresponds to each layer. (10 points)
b) What are http connections types? What is the main differences between them? (10 points)
c) Consider the pipelined reliable data transfer (rdt) protocols discussed in class over the channel that can corrupt or lose packets. (12 points or 4 each)
I. What is the benefit of the sequence numbers for these protocols?
II. What is the benefits of the introduced timers in these protocols?
III. What is the benefits of the introduced sliding window in these protocols?
Question 2: Consider sending a 2400-byte datagram into a link that has an MTU of 700 bytes. Suppose the original datagram is stamped with the identification number 422. (20 points)
a) How many fragments are generated? (4 points)
b) What are the values in the various fields in the IP datagram(s) generated related to fragmentation? (length, ID, fragflag, offset). (16 points)
Question 3: A node that has an IP address 200.166.60.55/20. what is the network address, broadcast address, and the IPs given range? (show work of your calculation then write your final answers in the table). (15 points)
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Network IP address |
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Broadcast address |
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IPs given range |
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Question 4: Suppose the TCP packet transmission between host A and host B (or a client and a server) follow the following scenarios, fill in the missing sequence number and ack number (for the TCP connection setup scenario, fill in the TCP packet flag value as well). (18 points)
TCP seq/ack number TCP connection setup
(Flag are the values used in TCP packet header flag field)
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connection |
Seq |
Ack |
data |
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connection |
Seq |
Ack |
Flag |
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3 |
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3 |
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Question 5: In this question, your will use Wireshark attached file to answer the following questions. The packets within each trace are stored in the libpcap file format, which can be opened and read by Wireshark. This carputer brought from different course CIS6395 and it is modified to fit this course. Provide screenshot of each part for full credits) (15 points or 5 each)
a) Haw many http packets in the capture and what filter you used?
b) There is a “PNG” image captured as it’s shown in the figure, what is the source IP, destination IP, protocol used, and the image dimension in pixels?
Fig. PNG image captured
c) ‘Ping’ program can be used to find out whether a remoter computer is online or not, or be used by attackers to do initial probing before real attacks. Identify the hosts that are running Ping in the traffic trace. Submit the list of IP addresses of the client computers that initiate Ping and the list of IP addresses of their targets. (you can use the screenshot only)