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CS447 - Networks and Data Communications
Possible Quiz Questions (Quiz #4)
For September 22nd, 2016
The following is a list of possible questions for our quiz on September 22nd. Some of the
questions will not be asked in the quiz. All the questions that will appear in the quiz will appear
exactly as shown below (however, numeric parameters may be changed). The quiz is closed
textbook, closed notes and closed neighbors. Note that the questions, which did not appear in this
quiz, still may appear in the exams. You will find a solution for these questions during lectures.
#1: Why is it difficult to determine “the optimum window size” for network connections
through the Internet? Mention two major reasons.
#2: What is the method TCP uses for determining “window size”?
#3: Is TCP slow-start slow in increasing the window size?
#4: What is “error control” for packet-switching networks?
#5: What are “undetectable errors”?
#6: Demonstrate how “undetectable errors” happen using parity-error detection.
#7: What are “uncorrectable errors”?
#8: Can “undetectable errors” be “correctable”?
#9: Why is “stop-and-wait ARQ” not popularly used?
#10: What are two “sliding-window based ARQ methods (just name the two)?
#12: What is the primary advantage of “GBN-ARQ” over “selective-reject ARQ”?
#13: What are the primary disadvantages of “GBN-ARQ” over “selective-reject ARQ”?
#14: What is the expected link utilization of selective-reject-ARQ (formula)?
#15: What is the expected link utilization of GBN-ARQ (formula)?
#16: What is “IP address” (what does each IP address represent)?
#17: Each IP address consists of two “addresses”. What are they?
#18: What is “domain address”?
#19: What is “host address”?
#20: Why does each IP address consist of two addresses of “domain address” and “host address”
(what is the motivation behind the design)?
#21: There are three different classes of IP addresses (Class A, B, and C). What was the primary
purpose of having three different classes?
#22: What is “subnet”?
#23: What is “subnet” for?
#24: Mention two purposes of subnet mask.
#25: Is “254.254.80.90” a valid subnet mask? If yes, how it is a valid subnet mask? If not, why
not?
#26: Given a following IP address: 191.56.98.201/10 and there are up to 64 sub-networks in that
domain, find the actual host address (without including the sub-network address) if the
domain’s subnet mask is “255.255.240.0”. Show all your work. Note: the parameters (the
IP address, IP prefix, the number of sub-networks and the subnet mask) will be changed in
the real quiz question.
#27: What does “CIDR” stand for?
#28: Why was CIDR introduced (i.e., what is the primary motivation of using CIDR)?
#29: How many host computers can exist for a network domain that has “/25” CIDR blockprefix?
#30: How do Internet core routers use CIDR block-prefix?
#31: Given a following IP address: 191.56.98.201/10 and there are up to 64 sub-networks in that
domain, find the sub-network address if the domain’s subnet mask is “255.255.240.0”.
Show all your work. Note: the parameters (the IP address, IP prefix, the number of subnetworks and the subnet mask) will be changed in the real quiz question.
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CS 447 – Networks and Data Communications, Quiz #4 Question List