Computer Networks Exam 1 Q&A
A client-server system uses a satellite network, with the satellite at a height of 40,000 km. What is the
best-case delay in response to a request (in msec)? - =533
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and
forward a packet through a switch. If switching time is 20 µsec, is this likely to be a major factor in the
response of a client-server system where the client is in New York and the server is in California? - =No
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and
forward a packet through a switch. If switching time is 20 µsec, what percentage of the trip time in the
response of a client-server system where the client is in New York and the server is in California is due to
switching delay? - =4
A server sends packets to a client via satellite. The packets must traverse one or multiple satellites
before they reach their destination. The satellites use store-and-forward packet switching, with a
switching time of 100 µsec. If the packets travel a total distance of 29,700 km, how many satellites do
the packets have to pass if 1% of the delay is caused by packet switching? - =10
Another advantage of having international standards for network protocols is that widespread use of
any standard will give it economies of scale, as with VLSI chips. - =True
If the unit exchanged at the data link level is called a frame and the unit exchanged at the network level
is called a packet, do frames encapsulate packets or do packets encapsulate frames? - =Frames
encapsulate packets
Layers one, two, and three of the OSI Model are implemented in the end systems but not in the routers
in the network core. - =False
One advantage of having international standards for network protocols is that if everyone uses the
standard, everyone can talk to everyone. - =True
One disadvantage of using international standards is that if everyone uses the standard, everyone can
talk to everyone. - =False
,Suppose that two network endpoints have a round-trip time of 100 milliseconds, and that the sender
transmits five packets every round trip. What will be the sender's transmission rate for this round-trip
time, assuming 1500-byte packets? - =5 × 1500 = 7,500 bytes per 100 milliseconds. So, the rate is 75,000
bytes per second.
Wireless networks have surpassed wired networks in popularity, even though they typically provide less
bandwidth. Select all the reasons listed below that are true and correct. - =Installing wires in buildings
can be expensive.
Wireless networks allow people to move around, instead of tying them to a wall.
A potential problem is battery life, since most wireless devices tend to be mobile.
Although wireless networks provide lower bandwidth than wired networks, their bandwidth has become
large enough to support applications that people find meaningful.
Wireless networks are by nature more secure than wired networks.
Which of the following descriptions below correspond to a "nuts-and-bolts" view of the Internet? - =A
collection of hardware and software components executing protocols that define the format and the
order of messages exchanged between two or more communicating entities, as well as the actions taken
on the transmission and/or receipt of a message or other event.
A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A platform for building network applications.
A "network of networks".
Which of the following descriptions below correspond to a "services" view of the Internet? - =A platform
for building network applications.
, A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A collection of hardware and software components executing protocols that define the format and the
order of messages exchanged between two or more communicating entities, as well as the actions taken
on the transmission and/or receipt of a message or other event.
Which of the following human scenarios involve a protocol? - =One person asking, and getting, the time
to/from another person.
A person sleeping.
A person reading a book.
A student raising her/his hand to ask a really insightful question, followed by the teaching
acknowledging the student, listening carefully to the question, and responding with a clear, insightful
answer. And then thanking the student for the question, since teachers love to get questions.
Two people introducing themselves to each other.
Which of the following physical layer technologies has the highest transmission rate and lowest bit error
rate in practice? - =Fiber optic cable
Choose one the following two definitions that makes the correct distinction between routing versus
forwarding. - =Forwarding is the local action of moving arriving packets from router's input link to
appropriate router output link, while routing is the global action of determining the source-destination
paths taken by packets.
Routing is the local action of moving arriving packets from router's input link to appropriate router
output link, while forwarding is the global action of determining the source-destination paths taken by
packets.
Which of the characteristics below are associated with the technique of packet switching? - =This
technique is used in the Internet.
Resources are used on demand, not reserved in advance.
A client-server system uses a satellite network, with the satellite at a height of 40,000 km. What is the
best-case delay in response to a request (in msec)? - =533
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and
forward a packet through a switch. If switching time is 20 µsec, is this likely to be a major factor in the
response of a client-server system where the client is in New York and the server is in California? - =No
A factor in the delay of a store-and-forward packet-switching system is how long it takes to store and
forward a packet through a switch. If switching time is 20 µsec, what percentage of the trip time in the
response of a client-server system where the client is in New York and the server is in California is due to
switching delay? - =4
A server sends packets to a client via satellite. The packets must traverse one or multiple satellites
before they reach their destination. The satellites use store-and-forward packet switching, with a
switching time of 100 µsec. If the packets travel a total distance of 29,700 km, how many satellites do
the packets have to pass if 1% of the delay is caused by packet switching? - =10
Another advantage of having international standards for network protocols is that widespread use of
any standard will give it economies of scale, as with VLSI chips. - =True
If the unit exchanged at the data link level is called a frame and the unit exchanged at the network level
is called a packet, do frames encapsulate packets or do packets encapsulate frames? - =Frames
encapsulate packets
Layers one, two, and three of the OSI Model are implemented in the end systems but not in the routers
in the network core. - =False
One advantage of having international standards for network protocols is that if everyone uses the
standard, everyone can talk to everyone. - =True
One disadvantage of using international standards is that if everyone uses the standard, everyone can
talk to everyone. - =False
,Suppose that two network endpoints have a round-trip time of 100 milliseconds, and that the sender
transmits five packets every round trip. What will be the sender's transmission rate for this round-trip
time, assuming 1500-byte packets? - =5 × 1500 = 7,500 bytes per 100 milliseconds. So, the rate is 75,000
bytes per second.
Wireless networks have surpassed wired networks in popularity, even though they typically provide less
bandwidth. Select all the reasons listed below that are true and correct. - =Installing wires in buildings
can be expensive.
Wireless networks allow people to move around, instead of tying them to a wall.
A potential problem is battery life, since most wireless devices tend to be mobile.
Although wireless networks provide lower bandwidth than wired networks, their bandwidth has become
large enough to support applications that people find meaningful.
Wireless networks are by nature more secure than wired networks.
Which of the following descriptions below correspond to a "nuts-and-bolts" view of the Internet? - =A
collection of hardware and software components executing protocols that define the format and the
order of messages exchanged between two or more communicating entities, as well as the actions taken
on the transmission and/or receipt of a message or other event.
A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A platform for building network applications.
A "network of networks".
Which of the following descriptions below correspond to a "services" view of the Internet? - =A platform
for building network applications.
, A place I go for information, entertainment, and to communicate with people.
A collection of billions of computing devices, and packet switches interconnected by links.
A collection of hardware and software components executing protocols that define the format and the
order of messages exchanged between two or more communicating entities, as well as the actions taken
on the transmission and/or receipt of a message or other event.
Which of the following human scenarios involve a protocol? - =One person asking, and getting, the time
to/from another person.
A person sleeping.
A person reading a book.
A student raising her/his hand to ask a really insightful question, followed by the teaching
acknowledging the student, listening carefully to the question, and responding with a clear, insightful
answer. And then thanking the student for the question, since teachers love to get questions.
Two people introducing themselves to each other.
Which of the following physical layer technologies has the highest transmission rate and lowest bit error
rate in practice? - =Fiber optic cable
Choose one the following two definitions that makes the correct distinction between routing versus
forwarding. - =Forwarding is the local action of moving arriving packets from router's input link to
appropriate router output link, while routing is the global action of determining the source-destination
paths taken by packets.
Routing is the local action of moving arriving packets from router's input link to appropriate router
output link, while forwarding is the global action of determining the source-destination paths taken by
packets.
Which of the characteristics below are associated with the technique of packet switching? - =This
technique is used in the Internet.
Resources are used on demand, not reserved in advance.
