CSCE 515: Computer Network Programming
Spring 2005
Homework 2 (Graduate)
02/24/05
1. (2 points) A UDP datagram sent from source address 129.252.11.254 to destination
address 224.0.0.2 is as follows. What is the correct value for the UDP checksum of this
datagram? (You can use either hexadecimal or binary representation.)
07
00
00
0a
76
31
81
c1
1c
00
6e
6c
31
fc
07
c1
?
10
0b
61
00
0b
03
00
6e
00
01
2. (1 point) Use Ethereal to capture all the fragments that belong to the same IP datagram
of size 10000 bytes. Save the captured packets in a file named “FRAGMENTxxxx”,
where xxxx stands for the last 4 digits of your SSN, and submit the file along with your
homework. Then answer the following question: What is the offset of every fragment?
(Hint: Generate an IP datagram of size 10000 bytes and transmit it over the department’s
network for capturing.)
3. (1 point) Use Ethereal to capture IGMP packets that the host menkar.cse.sc.edu uses
to join and leave the multicast group 234.5.6.7. Save the captured packets in a file
named “IGMPxxxx”, where xxxx stands for the last 4 digits of your SSN, and submit the
file along with your homework. (Hint: The IGMP implemented in menkar.cse.sc.edu
is Version 2, so a Leave Group packet will be sent out when menkar leaves a multicast
group.)
4. (1 point) Use Ethereal to capture DNS query packets for the domain name
www.uz.ac.zw. Save the captured packets in a file named “DNSxxxx”, where xxxx
stands for the last 4 digits of your SSN, and submit the file along with your homework.
Then answer the following question: What is the canonical name for www.uz.ac.zw?
You need to submit your neatly typed answers for the problems via the Dropbox named
homework02. In order to get the points, you need to explain your answer when you are
asked to. This homework is due on Mar. 4 at 11:59pm.