CS 1652 Final Exam
1. The exam is closed booked, closed notes.
2. You may not use a calculator.
3. All questions refer to the Kurose and Ross textbook. For example,
for the purposes of this test, assume Kurose and Ross explanation
of the TCP congestion control heuristics for any question dealing
with congestion control.
4. Answer on the exam sheet in the space provided.
5. The test is probably long, don’t dawdle.
6. Get to the point quickly in your answers.
1. (2 points) Within the context of cyclic redundancy checks (CRC) how
does the receiver detect bit errors?
2. (4 points) In CDMA host A wants to send host B the message 1
using code –1, 1, 1, 1, -1 and host C wants to send the message –1
to host D using the code –1, 1, -1, -1, -1. Show what A and C
transmit, what C and D receive, and what B and D view as the
3. (4 points) Assume that you have a 100 Mbps Ethernet segment where
the speed of the medium is 300,000,000 meters per second. How long
can the Ethernet segment be so that a node will be sure that it will
detect a collision? Recall the minimum sized frame is 576 bits. Show
4. (6 points) Assume you have a 100 Mbps physical medium on which
1000 users are trying to share. We consider two situations. In the
lightest situation, only 1 user is trying to use the medium. In the
heaviest situation, all 1000 users are trying to use the medium. For
each of the following MAC protocols, give the effective throughput
that you would expect for each of the lightest and heaviest situations.
Throughput is the number of bits per second that arrive at a receiver
that the bits were intended for.
b. Slotted Aloha. You may assume that the broadcast probability
is picked optimally in each situation.
5. (6 points) Assume that the host with IP address 220.127.116.11
sends a datagram packet to the host with IP address 18.104.22.168,
and then the host 22.214.171.124 sends a datagram to host
126.96.36.199. Give a linear list of the steps that are involved at the
network and link layer. Assume that the ARP tables are initially