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GEORGE MASON UNIVERSITY
COLLEGE OF BUSINESS
MIS740 PRACTICE QUESTIONS
Q1. In the SUB-1 cafeteria, customers make up their own salads on a plate and pay for it
based on weight. The graph of salad weight with respect to customer number represents
a (an) _______ signal.
a. amplitude modulated
weight
b. analog
of salad
c. digital
d. frequency modulated
1 2 3 4 5 6 7 8 9
e. none of the above
Customer #
Q2. The same cafeteria sells soft drinks in paper cups that come in three sizes - small,
medium and large. Customers walk up to a machine that dispenses Coke, Sprite and Root
Beer, pick up a paper cup and fill the cup themselves. Not all customers buy drinks. Soft
drink prices are 50cents, 75 cents and 90 cents for the three sizes respectively,
irrespective of brand name. The graph of drink price versus customer number represents
a (an) ________ signal.
a.
b.
c.
d.
e.
amplitude modulated
multiplexed
four level digital
binary digital
analog
Price of
Drink
1 2 3 4 5 6 7 8 9
customer #
Q3. Which of the following is NOT a characteristic of digital signals
a. they can only take on a discrete number of levels
b. they are harder to corrupt compared to analog signals
c. they cannot be carried on unguided media
d. they are less affected by phase delay distortion than are analog signals
Q6. Attenuation is one form of signal corruption. Attenuation reduces which
characteristics of a signal?
a. phase
b. bandwidth
c. frequency
d. amplitude
e. all of the above
Q7. Which of the following devices can be used to compensate for attenuation of an
analog signal?
a. a multiplexor
b. a repeater
c. data termination equipment (DTE)
d. an amplifier
e. all of the above
Q9. Pick the correct ranking of the following guided media in increasing order of
bandwidth (i.e. ranked lowest to highest)
a. twisted pair, multimode fiber, coaxial, single mode fiber
b. twisted pair, coaxial, multimode fiber, single mode fiber
c. coaxial, twisted pair, multimode fiber, single mode fiber
d. coaxial, twisted pair, single mode fiber, multimode fiber
e. twisted pair, coaxial, single mode fiber, multimode fiber
Q10. Choose the correct ranking of the following media in increasing order of cost, where
cost is measured in $/MHz/Meter. (i.e. lowest cost first)
a. single mode fiber, coaxial, multimode fiber, twisted pair
b. single mode fiber, twisted pair, coaxial, multimode fiber
c. twisted pair, coaxial, multimode fiber, single mode fiber
d. multimode fiber, twisted pair, single mode fiber, coaxial
e. single mode fiber, multimode fiber, coaxial, twisted pair
Q11. Choose the correct ranking of the following media in increasing order of error rates
(i.e. lowest error rate first)
a. multimode fiber, coaxial, twisted pair
b. twisted pair, multimode fiber, coaxial
c. multimode fiber, twisted pair, coaxial
d. coaxial, multimode fiber, twisted pair
Q12. Which of the following characteristics is NOT true of satellite (GSO) microwave
a. transmission delay is significantly higher than for terrestrial microwave
b. costs are quite insensitive to distance
c. error rates are about the same as for optical fiber
d. is good for point to multipoint type applications
e. is still used for transoceanic telephony
Q13. Which of the following techniques can be used to encode digital information as
analog signals?
a. differential PCM
b. FSK
c. Manchester encoding
d. amplitude modulation
e. frequency modulation
Q14. Which of the following techniques can be used to encode digital information as
digital signals?
a. PCM
b. PSK
c. Manchester encoding
d. Frequency modulation
e. differential PCM
Q18. Assume that the FSK method is being used to transmit digital information (1’s and
0’s) between two entities over a standard phone link (bandwidth 4000Hertz). How many
frequencies would you need in order to have full duplex communication?
a. one
b.two
c. three
d. four
e. four thousand
Q19. Which of the following are characteristics of the sliding window method of flow
control?
a. frames have sequence numbers
b. more than one frame may have to be retransmitted if an error occurs
c. it needs more buffer space compared to stop-and-wait
d. line utilization is higher than with stop-and-wait
e. all of the above
Q25. There are many different radio stations transmitting simultaneously over the
airwaves. You can tune in to any one of them on your car radio. The type of
multiplexing being used is
a. no multiplexing is necessary
b. frequency division multiplexing
c. time division multiplexing
d. statistical multiplexing
Q26. Which of the following are NOT characteristics of synchronous TDM?
a. every user is allocated a time slot whether or not they have something to send
b. The DS-1 standard for TDM can carry 24 voice channels
c. voice must be digitized before being carried using TDM
d. it needs separate buffers for each individual user being multiplexed
e. TDM cannot be used if optical fiber is the physical medium
Q1. Which of the following is NOT a characteristic of a PBX local network
a. it has a star topology
b. it is generally used to connect telephones
c. it has a star layout
d. offers higher speeds for data than LANs.
e. offers much lower speeds for data compared to LANs
Q2. Which of the following statements is true regarding an Ethernet type of LAN
a. must have a bus topology
b. may have a star layout
c. has reasonable delays only under light to moderate loads
d. commonly uses twisted pair or coaxial cable as its medium
e. all of the above are true
Q3. When a device connected to a CSMA/CD LAN detects a collision, which of the
following events take place
a. it stops transmitting immediately, waits a fixed amount of time, and retransmits entire
frame
b. it starts to retransmit entire frame immediately
c. it stops transmitting immediately, waits a random amount of time, then retransmits the
entire frame
d. it waits a fixed amount of time, then retransmits the remainder of the frame
e. none of the above
Q4 Which of the following characterizes the behavior of an IEEE802.3 type of LAN as
offered load is increased
a. the average delay increases drastically when offered load crosses a critical threshold
b. throughput first increases, then tapers off and starts decreasing
c. throughput increases steadily until it approaches nominal network capacity
d. packet size is automatically increased to reduce collision rate
e. a&b
Q5. Which of the following is NOT a characteristic of token ring LANs
a. A device can send a message only when it has a free token
b. Throughput keeps increasing gradually as offered load is increased
c. Delay increases only gradually as offered load is increased
d. Tokens occasionally get lost
e. The recipient of a message strips the payload and inserts a free token onto the LAN
Q6 Which of the following is NOT a characteristic of WANs
a. they may use a variety of transmission media throughout the network
b. there are several alternate paths between any given pair of sites
c. they may be private or public
d. information must be in the form of packets to be carried by WANs
e. they may use circuit or packet switching
Q7. Which of the following statements is NOT true of a circuit switched WAN
a. a complete path must be established before messages can be sent
b. is inefficient for bursty data
c. if offered load is too high, messages are blocked from entering the network at all
d. messages incur delay at each switch
e. was originally designed to carry voice
Q8 Which of the following statements about a packet switched WAN is false
a. may use the datagram or virtual circuit method
b. messages must be processed at each switch, incurring delay at each switch
c. if offered load is too high, messages can enter the network but delay will be high
d. it can be used to transmit real time voice conversations
e. packets can be of variable length
Q9. Which of the following statements about the IEEE802.5 standard is true
a. The nominal speed is 10MBPS
b. optical fiber is specified as the physical medium
c. coaxial cable is specified as the physical medium
d. shielded twisted pair is specified as the physical medium
e. all of the above
Q10. Which of the following statements about the X.25 standard is false
a. It uses the virtual circuit method of packet switching
b. packets can be of variable length
c. it uses the datagram method of packet switching
d. it is a standard for wide area networks
e. it uses CRC for error detection
Q11 10 points
(a) Consider an IEEE 802.3 type of LAN with 100 devices connected to it. Will the
number of collisions go up or down if the LAN is made longer keeping the number of
devices and their offered load the same? Briefly justify your answer.
Q12 [10 points]
A datagram packet switched WAN cannot carry real time voice since packets can take
different paths from source to destination. So packets can arrive out of sequence. Can a
virtual circuit packet switched WAN carry real time voice? Justify your answer briefly.
4 [10 points]
(a) the US has a nationwide power grid. So utilities can produce electricity anywhere and
send them anywhere it is needed. Would this network (i.e. the power grid) be analogous to
a circuit switched network or a packet switched network? Justify briefly
(b) You drop off letters at the local post office and it goes through various sorting centers
before finally arriving at its destination within the US or abroad. Is this postal network
analogous to a packet or circuit switched network ? Justify briefly.
5. Why is the ATM method able to handle real time voice, while Frame relay is unable to
do so, even though frame relay speeds are in the range of 1.5-40MBPS?
6. What is the difference between a bridge and router?
7. You have an ethernet LAN with TCP/IP running on top of it. If you need to connect
this LAN to an SNA network, would you use a bridge, router or a gateway? Justify
8. State two functions of layer 6 in the OSI model.
9. Why is a regular ethernet LAN not considered a switched network?
10. What is the main difference in the mechanics of operation between a fast ethernet LAN
and a switched ether net LAN?
11. We know that regular ethernet LANs, operating at 10MBPS, cannot handle real-time
voice very well. Would iyt be possible to send voice through a fast ethernet LAN
(100MBPS?)?