SOLUTIONS
Computer Networks, 6th edition
by Andrew S. Tanenbaum, Nick Feamster
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, Table of Content
1 Introduction
2 The Physical Layer
3 The Data Link Layer
4 The Medium Access Control Sublayer
5 The Network Layer
6 The Transport Layer
7 The Application Layer
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8 Network Security
9 Reading List and Bibliography
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PROBLEM SOLUTIONS 1
SOLUTIONS TO CHAPTER 1 PROBLEMS
1. Because the raven flies at an average speed of 40 km/h, it needs 160/40 = 4
hours for each one-way trip.
(i) The raven makes only one trip because 1.8 terabytes exactly fits on one
scroll.
1800 GB 1
= GB/s = 1 Gbps
4 h 3600 8
(ii) To communicate 3.6 TB of data, the raven has to fly back to pick up a
second scroll. This means that it needs to fly a total of 3 4 = 12 hours.
3600 GB 1 2
= GB/s = Gbps
12 h 3600 12 3
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(iii) The receiving castle receives 1.8 terabytes of data every 8 hours.
1800 GB 1 1
= GB/s = Gbps
8 h 3600 16 2
2. There are multiple correct answers. A significant disadvantage is the
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increased risk of invading people’s privacy. The increase in the number of net-
worked devices means a larger attack surface for malicious parties trying to
obtain personal information. If the information is not stolen, companies that
process and store data from IoT devices could sell it to third parties such as
D
advertising companies.
3. Secondly, wireless networks allow people to move around, instead of tying
them to a wall. Secondly, although wireless networks provide lower band-
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width than wired networks, their bandwidth has become large enough to sup-
port applications that people find meaningful. Examples include media
streaming and video conferencing. Finally, installing wires in (old) buildings
can be expensive.
4. An advantage for the company is that they do not have to pay the up-front cost
when buying expensive hardware. They lease machines from the data center,
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paying only for what they use. A disadvantage for the company is that they
may not know the underlaying infrastructure used by the data center, making it
more difficult to obtain high performance from their applications. The large
amount of resources available in data centers makes it is easier for the com-
pany to scale with user demand, which is an advantage for both. A disadvan-
tage for the users is that it becomes more difficult to track their own data, and
what it is used for.
, ST
U
D
YL
AB
Computer Networks, 6th edition
by Andrew S. Tanenbaum, Nick Feamster
ST
U
D
YL
AB
, Table of Content
1 Introduction
2 The Physical Layer
3 The Data Link Layer
4 The Medium Access Control Sublayer
5 The Network Layer
6 The Transport Layer
7 The Application Layer
ST
8 Network Security
9 Reading List and Bibliography
U
D
YL
AB
, kjhgfds
PROBLEM SOLUTIONS 1
SOLUTIONS TO CHAPTER 1 PROBLEMS
1. Because the raven flies at an average speed of 40 km/h, it needs 160/40 = 4
hours for each one-way trip.
(i) The raven makes only one trip because 1.8 terabytes exactly fits on one
scroll.
1800 GB 1
= GB/s = 1 Gbps
4 h 3600 8
(ii) To communicate 3.6 TB of data, the raven has to fly back to pick up a
second scroll. This means that it needs to fly a total of 3 4 = 12 hours.
3600 GB 1 2
= GB/s = Gbps
12 h 3600 12 3
ST
(iii) The receiving castle receives 1.8 terabytes of data every 8 hours.
1800 GB 1 1
= GB/s = Gbps
8 h 3600 16 2
2. There are multiple correct answers. A significant disadvantage is the
U
increased risk of invading people’s privacy. The increase in the number of net-
worked devices means a larger attack surface for malicious parties trying to
obtain personal information. If the information is not stolen, companies that
process and store data from IoT devices could sell it to third parties such as
D
advertising companies.
3. Secondly, wireless networks allow people to move around, instead of tying
them to a wall. Secondly, although wireless networks provide lower band-
YL
width than wired networks, their bandwidth has become large enough to sup-
port applications that people find meaningful. Examples include media
streaming and video conferencing. Finally, installing wires in (old) buildings
can be expensive.
4. An advantage for the company is that they do not have to pay the up-front cost
when buying expensive hardware. They lease machines from the data center,
AB
paying only for what they use. A disadvantage for the company is that they
may not know the underlaying infrastructure used by the data center, making it
more difficult to obtain high performance from their applications. The large
amount of resources available in data centers makes it is easier for the com-
pany to scale with user demand, which is an advantage for both. A disadvan-
tage for the users is that it becomes more difficult to track their own data, and
what it is used for.
, ST
U
D
YL
AB
