Quiz
Exam 1
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Perguntas do quiz (25)
1Which of the following is not one of the guidelines of a physical layer
standard?- AWhat kind of cable to use.
- BWhat connectors to use
- CHow the messages will be formatted.
- DHow the cables and devices should be arranged.
2In class, I explained the physical layer as being the truck, and that only a
truck can deliver messages. Which one of the following truck metaphors
are not true to how the physical layer works?- APhysical links are needed between all devices on a network, just like you
need a truck to deliver messages - BA new physical link will be followed after a frame hits a switch, just like
your message will be loaded into a new truck at the post office. - CA message arrives at a device all at once, just like a truck pulls up to a
loading dock and unloads packages. - DAll of the above are true about how the physical layer works.
- APhysical links are needed between all devices on a network, just like you
3Which of the following correctly describes the propagation effect?
- AAttenuation: a light beam becomes dimmer the further away it is from the
sender. - BDistortion: other signals get mixed in with the sender's signal.
- CAttenuation: the part of the signal that follows a direct path reaches the
receiver first. - DInterference: for media with low attenuation, interference limits link length.
- AAttenuation: a light beam becomes dimmer the further away it is from the
4Which of the following correctly describes why there is a length limit for
wireless links?- ADistortion of the radio waves caused by multipath interference makes it so
it is hard to tell a one from a zero. - BInterference from intermittent noise sources like lightning strikes means
that the sender must be very close to the receiver. - CAs a signal propagates, it becomes entangled with more than 16 photons
and the receiver can only untangle an octet. - DWhen you reach the point where the signal has attenuated so much that
you can no longer read it over background noise, you are too far away.
- ADistortion of the radio waves caused by multipath interference makes it so
5An IP address typically uses 8 bits to identify each host, meaning that
each host on a subnet must have a different combination of these bits in
that part of their address. How many different values can be represented
using 8 bits?- A64
- B16
- C256
- D65,536
6In typical signaling over copper cable, a certain type of voltage is used to
represent 1s, while another represents 0s. This makes it easy to tell the
difference between a 1 and a 0. Which of the following is true?- AA negative voltage is used for 1s while a positive voltage is used for 0s.
- BA high voltage is used to represent 1s while no voltage represents 0s.
- CThe voltage used for 1s is twice as high as the one used for 0s
- DA high voltage is used to represent 0s while no voltage represents 1s.
7What is the difference between binary and digital signals?
- ABinary signals send multiple bits per clock cycle
- BDigital signals are clearer than binary signals.
- CDigital signals have more resistance to propagation errors
- DBinary signals have two states
8On a wire that can only support 100K cycles per second, how can you
send 400Kbps?- AIf there are three states
- BIf there are eight states.
- CIf there are 16 states.
- DIf there are four states
9Using 100Base-TX, how do you get full-duplex transmission?
- ATwo connections involving four devices can be made over the same cable.
- BOne wire pair is used for sending signals, while another wire pair is used to
receive - CAll eight wires are twisted together.
- DFour wire pairs x two wires per pair = full duplex.
10DSL uses the same unshielded twisted pair cabling that phone companies
installed for telephone service, while cable modem service uses the
shielded coaxial cabling that cable companies installed for television
service. Which of the following correctly describes the difference between
DSL and cable Internet service?- APhone wires from everyone's house in a neighborhood get grouped
together in trunk lines, so each house has even higher capacity - BThe phone company's cables are immune from crosstalk interference.
- CThe cable company ran separate cables to each person's house, so cable
customers have QoS guarantees. - DCoaxial cabling is resistant to interference, so higher bit rates are possible
over a wide bandwidth.
- APhone wires from everyone's house in a neighborhood get grouped
11When I was in Tulsa, we hired some ex-students to wire a computer lab to
Cat 5 specifications for us. Which of the following wiring practices they
used was okay according to Cat 5 specifications?- AThe longest cable run was 20 meters.
- BSolid cable with RJ45 connectors was used for the runs to the
workstations. - CThe wires were untwisted 1 inch at the connectors
- DAll of the above violated Cat 5 specifications
12Optical fiber is typically only used for trunk lines and not for access lines.
Which of the following is false about the difference between fiber and
UTP?- AOptical fiber has high capacity.
- BCopper cable is easier to connectorize.
- COptical fiber is susceptible to interference.
- DOne copper cable has enough capacity for just about any network user.
13Which of the following is not a reason why fiber is considered the Cadillac
of network media?- AIt is possible to add light sources, increasing the possible transmission
speed on the same installed cable. - BSingle mode fiber can carry signals over long distances with low
attenuation. - CThere are a wide variety of different fiber connectors, so you have to be
sure to get the right kind. - DMultimode fiber can carry signals a few hundred meters with a high
capacity.
- AIt is possible to add light sources, increasing the possible transmission
14In the network at my house, all of my devices connect to a single switch.
What is the name of my network topology?- AStar
- BExtended Star
- CMesh
- DBroadcast/Bus
15My house has wired outlets in every room. However, if the wireless
connection ever goes out, I take a lot of grief until it is working again.
Which of the following is not a reason that I need to have a wireless
network connection available in my house?- AAn iPhone can only use a wireless network connection.
- BA wireless connection is faster than a wired connection.
- CMy wife occasionally sits on the porch with her laptop and it would be very
expensive to run a cable there. - DSometimes I like to play online with my son, and it is fun to be next to him
in the same room without having to run a long cable to an outlet in another
room
16Normally, WiFi is limited to 100 meters. However, some enterprising
people have setups where WiFi links travel several kilometers. What
makes this possible?- AUsing a dish antenna instead of an omnidirectional antenna
- BMaking sure that nothing is in between the antennas - trees, walls, etc
- CIncreasing the power of the transmission above what is approved by the
FCC. - DAll of the above would probably be necessary.
17802.11g used the 2.4 Ghz band while 802.11a used the 5.0 Ghz band.
Which of the following is false about the difference between 802.11g and
802.11a?- AWhen you moved away from an 802.11g access point, there was less
attenuation loss than moving the same distance away from an 802.11a
access point. - B5.0 Ghz is more than twice as powerful as 2.4 Ghz
- CThere was more bandwidth available at 5.0 Ghz, so 802.11a could deal
with things like multipath interference better. - DAn 802.11a was far more likely to be blocked by walls and other obstacles
than 802.11g.
- AWhen you moved away from an 802.11g access point, there was less
18802.11n uses basically the same frequencies as 802.11a and 802.11g,
and also uses OFDM. However, it transmits at up to 600 Mbps instead of
54 Mbps. Which of the following is not one of the ways that it achieves a
higher data rate?- ABy increasing the channel size to 40 MHz instead of 20MHz.
- BBy using dish antennas instead of omnidirectional antennas.
- CBy decreasing the S/N ratio using multiple antennas (MIMO).
- DBy using more channels in the less crowded 5.0 GHz band.
19Shortly after they moved in, our neighbors invited us to their home for a
lovely brunch. One of the topics of conversation was my latest home
improvement project, wiring our home with Cat 5 cable. After seeing that
my hands were rather scratched from poking around inside my walls, my
neighbor remarked that he had put a wireless network in his home that
was working just fine. Which of the following is not true about the
difference between my project and his?- APulling cable relaxes me so it hardly felt like work while I was doing it, so
the extra time I spent was worth it. - BI used the best cable available at the time, Cat 5e, which means I can
support very high transmission speeds. - CThe signals in my cables have no problems reaching from my basement to
the attic - DHis network cost a lot more in equipment and materials than mine.
- APulling cable relaxes me so it hardly felt like work while I was doing it, so
20Verizon is losing landline phone and DSL customers so rapidly that some
analysts say that Verizon has given up completely on local phone service.
However, Verizon's CEO is quick to crow about how much money they
make from FIOS customers. Why doesn't Verizon upgrade everyone to
FIOS?- ABecause FIOS is always on, and the power requirements would be too
high. - BBecause FIOS only goes up to 56 kbps, and too many customers would
overwhelm their network. - CBecause DSL uses existing copper lines and FIOS requires pulling new
fiber lines. - DBecause FIOS was only installed for the customers they gained when they
bought out GTE.
- ABecause FIOS is always on, and the power requirements would be too
21In December 2008, the city of Portsmouth renewed its franchise
agreement with Cox Communications. As part of the agreement, Cox
agrees to pay the city a fee of 35 cents per subscriber along with a
franchise fee equal to 5 percent of the company's gross revenues. What
did the city give to Cox in return?- AThe right of way to run cable along easements in the city.
- BA monopoly on telephone service in Portsmouth.
- CFree rent.
- DA sponsorship deal.
22Up until the mid 1990s, Internet service was only available by using a dial
up connection or a leased line from a phone company. Currently, cable
television companies dominate broadband internet service. Which of the
following is false about cable internet service?- ABandwidth is shared in a neighborhood.
- BCable companies pulled new cables to homes in order to offer internet
service. - CAdding optical nodes increases the amount of bandwidth available.
- DThe cable company controls what the cable modem can do.
23My wife's parents live in a house in a tiny town in Colorado that until
recently had no Internet service. They have electrical and phone service,
but their home is too far from the telephone company switching office to
get DSL. Recently, a company offered them Internet service using a
wireless link from an omnidirectional antenna on their roof to an
omnidirectional antenna on a cellphone tower about a mile away. Which
of the following is true about this internet service when compared with
DSL?- AThe installation costs are 2-3 times as much as DSL
- BTheir latency would be 100x worse than DSL.
- CTheir transmission speed will be worse than DSL
- DRain or trees between their antenna and the cellphone tower could
interrupt wireless service.
24The term modem actual stands for "Modulator/Demodulator." To modulate
a 0, an early modem played a 1,070 Hz tone. It modulated a 1 by playing
a 1,270 Hz tone. The demodulation process worked in reverse by
listening to the tones and converting them to bits. Which of the following is
true about this modem standard?- AThere are two possible states.
- BThe maximum speed is 1,270 bps.
- CThe clock rate is 1,070 cycles per second.
- DThere are two bits per clock cycle.
25Which of the following correctly describes the difference between using
commercial wireless data services like LTE/5G and using WiFi at your
home, ODU, a cafe, or a friend's house?- ACommercial services use licensed spectrum.
- BYou can get WiFi access anywhere you can drive a car.
- CCommercial wireless is free, while you would normally chip in if you used
your friend's WiFi. - DWiFi limits the number of applications you can use.
Informações
- Descrição
- Quiz sobre Exam 1, criado por Thomas Mayfield em 03-10-2022.
- Autor
- Thomas Mayfield
- Idioma
- English
- Visualizações
- 1
- Avaliação
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