Chapter 5 Solutions

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Guide to Net working Essentials, 4e


Chapter

5


1

Chapter
5

Solutions


Review Questions

1.

The OSI reference model divides networking activity into how many layers?


Answer: c.
seven


2.

With the OSI reference model, the job of each layer is to provide services to the next
-
higher layer
and to make accessible th
e details of how its services are implemented. True or false?


Answer: False


3.

The addition of information to a PDU as it is passed from one layer to the next

is called ______.


Answer:
b. encapsulation


4.

Layers that act as if they communicate directly with
each othe
r across the network are

called
______.


Answer:
d.

peers


5.

Write
the number that corresponds
to each of the following layers in the OSI reference model (
for
example, 7 = top, 1 = bottom).


Answer: a. 6, b. 2, c. 5, d. 1


6.

The
_________________

lay
er handles the creation of data frames.


Answer: Data Link


7.

Which layer handles flow control, segmentation of data, and error recovery?


Answer:
c.

Transport


8.

The ________________ layer governs how a network adapter must be attached to the networking
medi
um.


Answer: Physical


9.

Which layer determines the route a packet takes from sender to receiver?


Answer: c. Network


10.

The
______________
layer handles conversion of data from platform
-
specific application formats
to a generic, network
-
ready representation (
and vice versa).



Answer: Presentation


11.

Which layer is responsible for setting up, maintaining, and ending ongoing exchanges of
information across a network?


Answer: c. Session


12.

The
______________
layer handles segmentation of large amounts of
data for transmission and
reassembly of segmented data on receipt.



Answer: Transport


13.

A family of related n
etworking protocols is called a protocol ______.


Answer: b. suite


14.

Which of the following elements might occur within a data frame? (Choose all t
hat

apply.)


Answer: a, b, c, d


Guide to Net working Essentials, 4e


Chapter

5


2

15.

CRC is an acronym for ______.


Answer:
b
. Cyclical

Redundancy Check


16.

How many times is a CRC calculated?


Answer:
c.
twice; once before transmission and again on receipt


17.

Of the following Project 802 specifications, which
belong at the MAC sublayer
?


Answer:
b. 802.2



18.

Which layer of the OSI reference model does Project 802 break into two sublayers?


Answer: b. Data Link


19.

What are the names of the two sublayers specified as part of Project 802? (
Choose

two

answers.)


Answer
: b, d


20.

Which term refers to stripping of header information as a PDU is passed from one layer to a higher
layer
?


Answer:
a. de
-
encapsulation


21.

Which IEEE 802 standard applies to Ethernet?


Answer: b
. 802.3


22.

Which IEEE 802 standard applies to token ring?


Answer: d. 802.5


23.

Which IEEE 802 standard applies wireless PANs?


Answer:
d
. 802.
15


24.

Which IEEE 802 standard applies to wireless
LANs
?


Answer:
e.

802.11


25.

What is the name of the PDU found at the Transport layer
?


Answer:
c
.
segment


26.

Which of the following

acronyms represent popular protocol suites? (Choose all that

apply.)


Answer: a, b


27.

Which of the following definitions best describes a redirector?

Answer:
c.

a software service that handles resource requests, passes on local requests for local
service, a
nd redirects network access requests to the appropriate network server or

service


28.

Which of the following are examples of software found at the Application layer?
(
Choose all that
apply).


Answer:
a, c



29.

At which
Data
-
Link
sublayer does the network address

burned into every NIC reside?


Answer:
a.
Media Access Control (MAC) sublayer


30.

Which of the following
can occur
at the Physical layer? (
Choose
all that apply
.
)


Answer:
c. signal errors caused by noise


Guide to Net working Essentials, 4e


Chapter

5


3

Hands
-
on Projects

Project
5
-
1



Project
5
-
3

No answers necessary
.



Case Projects

Case Project 1

Answers will vary. Students should show results that reflect the information found on the
www.protocols.com

web site.


Case Project 2

All of these are reasonable arguments. It may not matter to your b
oss whether it is an "accepted industry
standard,” but it will make drivers and devices easier to find. Speed is always an issue, and the fact that

Ethernet moves at 10 Mbps should be an incentive. Of course, 100 Mbps is available and prices are
dropping,
so it is an even more attractive technology. The fact the Ethernet can run on many media that are
resistant to interference makes it a likely choice for
getting the shop floor connected.


Case Project 3

Many companies do indeed elect to install Category 5
twisted
-
pair cabling on their premises nowadays,
even if they do not plan to use 100 Mbps technologies right away. That’s because the cost of installing
cable is usually 3 to 10 times greater than the cost of the cable itself

in plain English, this means t
hat
installation costs dwarf media costs, so it’s wise to install the fastest media you can afford any time you
must install cabling of any kind. For this case, answer a is clearly correct. Also, because Ethernet uses the
same frame format across all media

and technologies, it’s true that all the flavors of Ethernet interoperate
without requiring segmentation of payloads when moving from faster to slower technologies (as is the case
with token ring). Thus, answer b is also correct. Answers c and d are both
red herrings because, while they
do speak to legitimate phenomena

that is, installation savings may very well offset the costs of new NICs
and hubs later on, and higher speeds usually do improve productivity

the case does not present sufficient
information

to permit you to draw either of those two conclusions. So, answers c and d are both incorrect.



Case Project 4

Because of the information presented in the case, it’s clear that Ethernet versions interoperate together
without requiring segmentation. Likew
ise, it’s also clear that Ethernet versions cover a broader range of
bandwidths

up to 1 Gbps, in fact

than token ring versions do. Thus, answers a and c are correct
(because they accurately restate information presented in the case), and answers b and d ar
e incorrect (since
they assert the opposite of what the case lays out).