Data Communication & Networking Quick Study

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Data Communication & Networking Quick Study

Rosmaizura binti Abd Razib
Juliana binti Md Jusoh

Politeknik Kota Bharu

i

Published and printed by:
Department of Electrical Engineering
Politeknik Kota Bharu

KM. 24, Kok Lanas, 16450 Ketereh, Kelantan
Data Communication & Networking Quick Study
Edition issue 2022
© Rosmaizura binti Abd Razib
© Juliana binti Md Jusoh

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system,
or transmitted in any form or by any means, electronic, photocopying, recording or otherwise,
without the prior written permission of the Department of Electrical Engineering, Kota Bharu
Polytechnic.

Data Communication & Networking Quick Study / Rosmaizura binti Abd Razib & Juliana binti
Md Jusoh

ii

APPRECIATION

Thanks to Allah s.w.t for the strength that has been given to us in preparing this book. We
would also like to take this opportunity to thank the Head of the Electrical Engineering
Department, Madam Fatimah binti Ab Rahman for the encouragement given. The same
speech was also addressed to our e-Learning Coordinator of the Electrical Engineering
Department, Madam Sheilani binti Shaari who also has contributed ideas to further
strengthen the writing of this book. Thanks also to those who have played a direct or indirect
role in the success of this book. Lastly, special thank you to our beloved family who has given
us lot of moral support.

Rosmaizura binti Abd Razib
Juliana binti Md Jusoh
Department of Electrical Engineering
Politeknik Kota Bharu
KM. 24, Kok Lanas, 16450 Ketereh, Kelantan

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ABSTRACT

This book is produced to help students who take the DEP50033 Data Communication &
Networking course. This course is compulsory for students under Diploma in Electronic
Engineering (Communication) (DEP) program and is an elective course for Diploma in
Electrical Engineering (DET) and Diploma in Electrical & Electronics Engineering (DEE)
students. Data Communication & Networking Quick Study is a book produced to help students
in reviewing lessons quickly and easily. It contains a collection of past examination questions
starting from the June 2019 session until June 2016 complete with answers according to the
scoring system used in the examination at the polytechnic. Data Communication &
Networking Quick Study is written using English and align with the syllabus to make it easier
for students to use it. In the writing of this book, each question is grouped according to the
topics found in the Data Communication & Networking course. The answers provided are
written concisely so that it is easier for students to understand.

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ABOUT AUTHOR

Rosmaizura binti Abd Razib was born in Pasir Mas, Kelantan on 19 July
1981. Successfully obtained excellent results at the SPM level and then
continued her studies to the Matriculation level in Kuantan, Pahang
(1999). Obtained a Bachelor's Degree in Electrical Engineering from Tun
Hussein Onn University of Technology (2005). She started her job as a
lecturer in the Department of Information & Communication
Technology, Ungku Omar Polytechnic (2006). She is currently working as a lecturer at the
Department of Electrical Engineering, Kota Bharu Kelantan Polytechnic. She has been
teaching in the field of telecommunications for 16 years. In the field of administration, she
was the Assistant of a Head Program for DET at the Department of Electrical Engineering of
Kota Bharu Polytechnic . She is active and contributes a lot in the development programs of
students, school children, government employees and even private agencies.

Juliana binti Md Jusoh was born in Jerteh Besut Terengganu on 18 April
1983. Successfully obtained excellent results at the SPM level and then
continued his studies to the Diploma level at Universiti Teknologi Mara
(2001). Obtained a Bachelor’s Degree in Electrical Engineering from the
same university in 2007.Then she continued her studies on Master of
Electrical and Electronics Engineering at Universiti Teknikal Malaysia
Melaka (2013). She is currently working as a lecturer at the
Department of Electrical Engineering, Kota Bharu Kelantan Polytechnic. She started working
at the Polytechnic in September 2009. She has been teaching in the field of
telecommunications for 12 years. In the field of administration, she was Head of Program for
DET at the Department of Electrical Engineering of Kota Bharu Polytechnic for 1 year and
Secretary of ETAC accreditation at Kota Bharu Polytechnic from 2019 until now. She is active
and contributes a lot in student development programs.

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TABLE OF CONTENTS iii
iv
APPRECIATION v
ABSTRACT vi
ABOUT AUTHOR 1
TABLE OF CONTENTS 13
20
CHAPTER 1: BASIC CONCEPT OF DATA COMMUNICATION 27
CHAPTER 2: INTRODUCTION TO NETWORKING 35
CHAPTER 3: OPEN SYSTEM INTERCONNECTION (OSI) MODEL AND PROTOCOL 41
CHAPTER 4: LOCAL AREA NETWORK
CHAPTER 5: PUBLIC DATA NETWORK
REFFERENCES

vi

CHAPTER 1: BASIC CONCEPT OF DATA COMMUNICATION

Data communications refers to the transmission of this digital data between two or
more computers and a computer network or data network is a telecommunications
network that allows computers to exchange data.

A communication system is made up of the following components: Information
Source, Transmitter (Tx), Transmission Medium or Communication Channel, Receiver
(Rx), Destination. For a data packet to be appropriately transmitted on a network, it
needs to be converted into the best and most reliable way of transmission. For this
reason, data is encoded in a way that is best understood by computers.

The data encoding technique is divided into the following types, depending upon the
type of data conversion; Digital to Digital, Analog to Analog, Digital to Analog. In
digital-to-digital encoding there are Non-Return-to-zero (NRZ), Return to Zero (RZ),
Manchester, Alternate Mark Inversion (AMI), High Density Bipolar 3 Zero (HDB3),
Multi Transmission Three Level and Four Binary/Five Binary (4B/5B).

Whenever a message is transmitted, it may get scrambled by noise or data may get
corrupted. To avoid this, the error-detection codes which are additional data added
to a given digital message to help us detect if any error has occurred during
transmission of the message. Two types of error detection techniques used are
Vertical Parity Check (VRC) and Cyclic redundancy check (CRC)

1

QUESTION 1
There are three types of data conversion techniques such as, Digital-to-Digital encoding,
Analog-to-Digital encoding and Digital-to-Analog encoding. List FOUR (4) types of Digital-to-
Digital data encoding.
Answer

i. Non Return To Zero
ii. Return Zero
iii. Manchester
iv. Bipolar AMI (Alternate Mark Inversion)
v. High Density Bipolar Order 3 (HDB3)
vi. Multiline Transmission, Three Level (MLT-3)
vii. Four Binary/Five binary (4B/5B)

(choose 4 answer only: total = 4 marks)

QUESTION 2
Using Non Return to Zero (NRZ) and Alternate Mark Version (AMI) encoding methods, draw
the output waveform for 11001101. Assume the start at positive voltage.
Answer
NRZ

(0.5 mark for each signal: total = 4 marks)

2

AMI

(0.5 mark for each signal: total = 4 marks)
QUESTION 3
List THREE (3) elements of data communication according to the Claude Shannon’s General
Communication Model.
Answer
From above Claude Shannon’s basic Communication block diagram, there are five elements
basic communications system which are:

i. Information source
ii. Transmitter (Tx)
iii. Transmission Medium or Communication Channel
iv. Receiver (Rx)
v. Destination

(Choose 3 answer only: total = 3 marks)
QUESTION 4
With the use of digital waveform, determine the AMI (Alternate Mark Inversion) and
Manchester by using the data below:
11001
Answer

(0.5 mark for each signal: total = 2.5 marks)
3

(0.5 mark for each signal: total = 2.5 marks)
QUESTION 5
Given data m(x) =101010, g(x)=1001 and 3 remainder bit = 100. Apply the CRC (Cyclic
Redundancy Check) technique to detect the error at the receiver.
ANSWER

(7 marks)

4

QUESTION 6

Given TWO (2) data in polynomial, first data m1(x) =10011010 and second data m2(x) =
10010110. The generator used is g(x) =1101 and remainder bit 101. Anaylze the CRC (Cyclic
Redundancy Check) technique to detect the error at the receiver and identify the type of
error for the first and second data if any.

ANSWER

(10 marks)

Second data m2(x) = 10010110.

(10 marks)
5

QUESTION 7
State THREE ( 3 ) processes in Pulse Code Modulation (PCM).
ANSWER

i. Sampling
ii. Quantizing
iii. Encoding

QUESTION 8
Explain how bit 1 and bit 0 are encoded by using Return Zero (RZ) and identify the bit
pattern by using the following data stream : 101101.
ANSWER
Bit 1 = +ve in 1st half and 0 in 2nd half

(1 mark)
Bit 0 = -ve in 1st half and 0 in 2nd half

(1 mark)

QUESTION 9 (0.5 mark for each signal: total = 3 marks)
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For the following data, by using Cyclic Redundancy Check (CRC) error checking, calculate the
CRC bit. Original Frame M(x) : 110101 Generator G(x) : 110
ANSWER

(7 marks)
QUESTION 10
Cyclic redundancy check is a method to check errors in data communication channel. Given
the data message is 11000 and the generator bit is 101, determine the cyclic redundancy
check (CRC) bit at the transmitter and the receiver. If the received message is corrupted and
the corrupted message is 1101011 at the receiver, determine the CRC check bit or the
remainder at receiver.
ANSWER
CRC BIT AT TRANSMITTER

(6.5 marks)
7

CRC BIT AT RECEIVER

(6.5 marks)

MESSAGE ERROR AT RECEIVER

CRC bit at receiver + 10 (1m)

(7 marks)

QUESTION 11

Describe Data Terminal Equipment (DTE) and Data Communication Equipment (DCE) by
giving ONE (1) example each.

ANSWER (1 mark)
DTE - The device in a data network that transmit and receive data
(0.5 mark)
Etc: mainframes, desktop computer, Pinter 8

DCE – devices that move information by implementing communications facilities.
(1 mark)

Etc: Modems, bridges, switch, gateway
(0.5 mark)

QUESTION 12
Determine the encoded waveform for 1010011100 data by using Alternate Mark Inversion
(AMI) encoding method.
ANSWER

(0.5 mark for each signal: total = 5 marks)
QUESTION 13
The data to be sent is 101010 and the CRC generator is 1011. Show that the CRC bit is 001
by using Cyclic Redundancy Check (CRC) technique.
ANSWER

(7 marks)
9

QUESTION 14

Given the data message is 10010 and the generator bit is 1011, determine the cyclic
redundancy check (CRC) check bit at the sender and the receiver. If the corrupted message
is 1000110 arrived at the receiver, determine the CRC check bit and identify the types of
error happened in the corrupted message.

ANSWER

CRC BIT AT THE RECEIVER

(6 marks)

CRC BIT AT THE TRANSMITTER

(6 marks)
10

QUESTION 15

List THREE (3) types of digital to digital encoding technique.

Answer

i. Non Return To Zero
ii. Return Zero
iii. Manchester
iv. Bipolar AMI (Alternate Mark Inversion)
v. High Density Bipolar Order 3 (HDB3)
vi. Multiline Transmission, Three Level (MLT-3)
vii. Four Binary/Five binary (4B/5B)

(choose 3 answer only, total =3 marks)

QUESTION 16

Every data communication system has 5 basic components. Referring to diagram A1 below;
Diagram A1

i. Namely A and B components.
ii. ii. Distinguish between A and B.

ANSWER component B: Receiver
i. component A : Transmitter

(2 marks)

ii. component A : Transmitter = a device that send a massage
component B : Receiver = a device that receive a massage

(2 marks)

QUESTION 17

The data encoding technique is divided into several types, depending on the type od data
conversion needed. List THREE (3) types of data encoding.

i. Analogue – to – Analogue Encoding
ii. Analogue – to – Digital Encoding
iii. Digital – to – Digital Encoding
iv. Digital – to – Analogue Encoding

(choose 3 answer only, total =3 marks)

11

QUESTION 18
There are several types used in digital transmission of binary information. Differentiate the
characteristic of RZ and NRZ in digital- to-digital encoding by using the encoded signal
diagram if the data signal is 01001.
The difference between RZ and NRZ is:

i. RZ encoding uses three values of voltage amplitude: positive (+ve), negative (-ve)
and zero
(0.5 mark)

ii. NRZ encoding uses the values of voltage amplitude: positive (+ve) and negative (-ve)
(0.5 mark)

(0.5 mark for each signal: total = 5 marks)

12

CHAPTER 2: INTRODUCTION TO NETWORKING

A computer network is a set of computers sharing resources located on or provided by
network nodes. The computers use common communication protocols over digital
interconnections to communicate with each other. These interconnections are made up of
telecommunication network technologies, based on physically wired, optical, and wireless
radio-frequency methods that may be arranged in a variety of network topologies.

There are two types of networks; peer-to-peer network and client server network and
classification of network consists of four: Local Area Network (LAN), Metropolitan Area
Network (MAN), Wide Area Network (WAN) and Global Area Network (GAN).
Networking cables are networking hardware used to connect one network device to other
network devices or to connect two or more computers to share printers, scanners etc.
Different types of network cables, such as coaxial cable, optical fiber cable, and twisted pair
cables, are used depending on the network's physical layer, topology, and size.

An Ethernet crossover cable is a type of twisted pair Ethernet cable used to connect
computing devices together directly that would normally be connected via a network switch,
Ethernet hub or router, such as directly connecting two personal computers via their network
adapters. Meanwhile a straight through cable is a type of twisted pair cable that is used in
local area networks to connect a computer to a network hub such as a router. This type of
cable is also sometimes called a patch cable and is an alternative to wireless connections
where one or more computers access a router through a wireless signal. Crossover cable uses
two different wiring standards: one end uses the T568A wiring standard, and the other end
uses the T568B wiring standard. The internal wiring of Ethernet crossover cables reverses the
transmit and receive signals. It is most often used to connect two devices of the same type:
e.g. two computers (via network interface controller) or two switches to each other. On a
straight through cable, the wired pins match. Straight through cable use one wiring standard:
both ends use T568A wiring standard or both ends use T568B wiring standard.

13

QUESTION 1
Local Area Network (LAN), Metropolitan Area Network (MAN), Wide Area Network (WAN)
and Global Area Network (GAN) are the classification of networks. Summarize the
characteristics and advantages for Local Area Network (LAN). Twisted pair cable is a type of
cable used in LAN networking. TIA/EIA 568A and TIA/EIA 568B are the two-colour codes used
for wiring twisted pair cable with the RJ45 connector under the Telecommunications Industry
Association (TIA)/Electronic Industries Alliance (EIA) wiring standard. With an aid of a suitable
diagram, propose the cable colour arrangement for TIA/EIA 568 A and TIA/EIA 568B.
Recommend an application for the connection of straight-through and crossover cable
ANSWER
Characteristic of LAN

i. the computers are relatively close together.
ii. LAN size is limited to a distance of several kilometres
iii. LANs would be within the same office, a single building, or several buildings close

together.
iv. Common LAN topologies are bus, star and ring.

(choose 3 answers only, total = 3 marks)

Advantages of LAN:
i. Hardware and software can be shared.
ii. Does not cost too much.
iii. Private ownership.
iv. All the user work can be stored in a central place hub.
v. Separate component.
vi. It is easy to set up a security protocol to protect the LAN user from hackers.

(choose 3 answers only, total = 3 marks)

(4 marks)
14

application for the connection of straight-through: (3 marks)
computer to hub (3 marks)
computer to switch
router to switch

application for the connection of crossover cable.
computer ke computer
hub ke hub
switch ke switch

QUESTION 2

Define peer to peer network.

ANSWER

i. Every computer can communicate directly with every other computer
ii. By default, no computer on a peer-to-peer network has more authority than another
iii. However, each computer can be configured to share only some of its resources and

prevent access to other resources
iv. more commonly implemented where less than ten computers are involved and

where strict security is not necessary.
v. each computer in the network act as both client or server for the other computers in

the network
vi. allowing shared access to files/email with every other computer on the network and

peripherals without the need for a central server
(7 marks)

QUESTION 3

Illustrate client/server network and carry out THREE (3) characteristics of client/server
network.

ANSWER

15

(2 marks)
i. Suitable for larger network
ii. A computer network in which one centralized
iii. Powerful computer is a hub to which many less powerful personal computers or

workstations are connected
iv. Clients run programs and access data that are stored on the server

(choose 3 answers only, total = 3 marks)

QUESTION 4
Name THREE (3) common elements required in a client/server network.
ANSWER

i. Client
ii. Server
iii. Nic

(3 marks)
QUESTION 5
Illustrate simple connection devices to show the use of a straight-through cable and cross-
over cable.
ANSWER

(choose 3 diagrams for each cable usage, total = 6 marks)

16

Use of straight through cable:
i. Switch to router
ii. Switch to PC or server
iii. Hub to PC or server
(3 marks)

Use of cross over cable.
i. Switch to switch
ii. Switch to hub
iii. Hub to hub
(3 marks)

QUESTION 6
Define network in data communication.
ANSWER
Networks comprise 2 or MORE computers that have been connected to share resources (
such as printer and CD), exchange data or make a electronic equipment

(2 marks)

QUESTION 7
With a suitable diagram, interpret peer to peer network.
ANSWER

i. more commonly implemented where less than ten computers are involved and
where strict security is not necessary.

ii. each computer in the network act as both client or server for the other computers in
the network

17

iii. allowing shared access to files/email with every other computer on the network and
peripherals without the need for a central server

iv. easy to install
v. low cost

(diagram = 2 marks, explain = 1 mark for each point, total = 7 marks)

QUESTION 8
List THREE (3) basic components of computer network.

ANSWER

i. NIC
ii. Transmission Medium
iii. Connectivity Devices

(3 marks)

QUESTION 9

Illustrate the usage of peep-to-peer network and client/server network and draw a suitable
diagram of each network.

ANSWER
Peer-To-Peer Network

(2 marks)
18

Client/Server Network

(2 marks)

PEER-TO-PEER NETWORK CLIENT/SERVER NETWORK

Easy to setup. More difficult to set up.

Less expensive. More expensive to install.

Can be implemented on a wide range A variety of operating systems can

of operating systems. be supported on the client computers,

but the server needs to run an

operating system that supports

networking.

Very low levels of security supported High levels of security are supported, all of

or none at all which are controlled from the server.

Ideal for networks with less than No limit to the number of computers

10 computers. that can be supported by the network.

(choose 3 answers for each network, total = 6 marks)

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CHAPTER 3: OPEN SYSTEM INTERCONNECTION (OSI) MODEL AND
PROTOCOL

The open systems interconnection (OSI) model is a conceptual model created by the
International Organization for Standardization which enables diverse communication systems
to communicate using standard protocols. It’s based on the concept of splitting up a
communication system into seven abstract layers, each one stacked upon the last.
A protocol is a set of rules that governs the communications between computers on a
network. Network protocols include mechanisms for devices to identify and make
connections with each other, as well as formatting rules that specify how data is packaged
into messages sent and received. The Transmission Control Protocol (TCP) and Internet
Protocol (IP) are the example of protocols used in OSI model.
The TCP/IP have four layers; Physical and Data Link Layers, Network Layer, Transport Layer
and Application Layer and there is a specific protocol for each layer. There are also four levels
of TCP/IP address; Physical (link) address, Logical (IP) address, Port address and Specific
address.

20

QUESTION 1
Explain any TWO (2) functions of TCP/IP layer.

ANSWER
Layer 1: NETWORK ACCESS

i. Responsible for carrying individual bits across the link
ii. The communication between two devices at physical layer is a logical

communication because there is another hidden layer, the transmission media
(choose 2 answer for each layer, total = 2 marks)

Layer 2: INTERNET LAYER
i. Responsible for moving the packet through the link. It takes a datagram and
encapsulates it in a packet frame.
ii. The routers in this layer are responsible for choosing the best link.
iii. Responsible for creating a connection between the source computer and destination
computer.
iv. Address of host destination
v. Exchange of data between end system and network.
(choose 2 answer for each layer, total = 2 marks)

Layer 3: TRANSPORT LAYER
i. Responsible for giving services to the application layer
ii. At source host, gets the massage from the application layer packet ( call segment
or a user datagram in different protocols) sends it through the logical connection,
to the transport layer at the destination host.
iii. also called host – to-host layer
(choose 2 answer for each layer, total = 2 marks)

Layer 4: APPLICATION LAYER
i. Provides services to the user
ii. Support each type of application such as fail transfer (FTP, HTTP, Telnet, SMTP,
News).
(choose 2 answer for each layer, total = 2 marks)
(Total = 4 marks)

21

QUESTION 2

By using a suitable diagram as reference, show the relationship between Transmission
Control Protocol (TCP/IP) protocol layer to Open System Interconnection (OSI) model layer.

ANSWER

(6 marks)

QUESTION 3

Determine the purpose of OSI (Open System Interconnection) model in data communication
and networking.

ANSWER

i. Initiate start and stop links
ii. Synchronize the transmission links
iii. Initiate start and stop links
iv. Accelerate the use of channel
v. Control the flow of the messenger

(choose 3 answers, total = 3 marks)

22

QUESTION 4
Relate the TCPIP (Transfer Control Protocol Internet Protocol) protocol layer with OSI (Open
System Interconnection) model layer.
ANSWER

(6 marks)
QUESTION 5
Relate the FOUR (4) levels address of TCP/IP (Transfer Control Protocol Internet) with TCP/IP
(Transfer Control Protocol Internet Protocol) layer.
ANSWER

(7 marks)
23

QUESTION 6
Describe ONE (1) function of the following Open Interconnection System (OSI) layer:
i. Presentation
ii. Transport
iii. Data Link
ANSWER

i. Presentation
• responsible for translation, compression, and encryption to allow both
devices (transmitter and receiver) to understand the particular transmission.

ii. Transport
• responsible for the overall delivery of messages from the sender-to- receiver.
• Ensure that packets are not lost during transmission and the packet is error-
free, in sequence, and not be copied
• set the protocol to structure the messenger and to check the validity of
transmission.

i. Data Link
• takes care of error detection and correction through the re-transmission of
messages
• responsible for ensuring the integrity of the bit streams that are transferred
to/from the physical layer from/to the network layer.
(1mark each answer: total 3 marks)

QUESTION 7
Relate the Transmission Control Protocol (TCP/IP) protocol layer to Open Interconnection
System OSI model layer.
ANSWER

(0.5m for each layer, 0.5m for each label OSI/TCP/IP: total = 6 marks)

24

QUESTION 8
Explain the function of physical layer in Open System Interconnection (OSI) model.
ANSWER

i. Concerned with the physical between devices
ii. It includes factors such as network topology, cable types, connector types, signal

modulation types.
iii. Responsible for transmitting a stream of binary digits from one device to another

(1 mark for each point: total= 3 marks)

QUESTION 9
Sketch the format of datagram packet for Internet protocol version 4 (IPV4) .
ANSWER

(0.5m for each layer: total=6 marks)

QUESTION 10
Kenneth’s boss wants him to connect 10 sets of computers which are located in the office.
Show a set of IP addresses which is suitable for this purpose and which network class should
this be? Given IP address 192.168.x.x. DIS2017
ANSWER
PC1 = 192.168.1.2
PC2 = 192.168.1.3
PC3 = 192.168.1.4
PC4 = 192.168.1.5

25

PC5 = 192.168.1.6

PC6 = 192.168.1.7

PC7 = 192.168.1.8

PC8 = 192.168.1.9

PC9 = 192.168.1.10

PC10 = 192.168.1.11

(0.5m for every IP: total= 5marks)

(*choose any Ip address in range 192.168.1.1-192.168.254.254)

• IP class C

(1 mark)

QUESTION 11

Explain the function of application layer in OSI modal (Open System Interconnection).

ANSWER

• Deals with the user
• This layer provided services to the user such as email, file transfer
• The Application Layer of the OSI model is responsible for providing end-user services,

such as file transfer, electronic messaging, e-mail, virtual terminal access, and
network management.

(1 mark for each point: total = 3 marks)

26

CHAPTER 4: LOCAL AREA NETWORK

A local-area network (LAN) is a computer network that spans a relatively small area.
Most LANs connect workstations and personal computers. Each node (individual
computer ) in a LAN has its own CPU with which it executes programs, but it also is
able to access data and devices anywhere on the LAN. This means that many users
can share expensive devices, such as laser printers, as well as data.
In IEEE 802 LAN/MAN standards, the medium access control (MAC) sublayer is the
layer that controls the hardware responsible for interaction with the wired, optical or
wireless transmission medium. There are three types of MAC; Carrier sense multiple
access/collision avoidance (CSMA/CA), Carrier sense multiple access/collision
detection (CSMA/CD) and Token passing.

CSMA/CA acts to prevent collisions before they happen. In CSMA/CA, as soon as a
node receives a packet that is to be sent, it checks to be sure the channel is clear (no
other node is transmitting at the time). In CSMA/CD every host has equal access to
the wire and can place data on the wire when the wire is free from traffic. In other
words, devices are in listen-before-transmit carrier sense mode. Token passing is a
deterministic methodology for ring networks in which all network devices play some
part in managing access to the transmission medium, using a small frame called the
token.

Wireless Local Area Network (WLAN) WLAN, for, refer to a Local Area Network that
does not need cables to connect the different devices. Instead, radio waves and IEEE
802.11 are used to communicate. Two types of services in WLAN; basic service set
(BSS) and Extended service set (ESS)

27

QUESTION 1

IEEE 802 is a networking standard developed by the Institute of Electrical and Electronic
Engineers. IEEE 802 is subdivided into 22 parts from 802.1-802.22 that explain the cover to
Data Link Layer and Physical Layer of ISO/OSI model. Elaborate two sub-layers in the Data
Link Layer.

ANSWER

Two sub-layers in the Data Link Layer

i. Logical link Control (LLC)
• Responsible to manage and ensure the integrity of data transmission, which is

provides data transmission method in different network
• Provides addressing and control data link.

(2 marks)

ii. Media Access Control
• Refer to sublayers that determines who allowed to access the media at any one time
• Determines where one frame of data ends and next one start- frame
synchoronization

(2 marks)

QUESTION 2

Local Area Network (LAN), Metropolitan Area Network (MAN), Wide Area Network (WAN)
and Global Area Network (GAN) are the classification of networks. Summarize the
characteristics and advantages for Local Area Network (LAN).

ANSWER

Characteristics of LAN:

i. LAN is a group of computers and associated devices that share a common
communications line or wireless link

ii. across the limited area, almost 5km
iii. permits the user (normally 10 to 1000 users) to share information or computers

sources includes data storages, printer, processor
iv. used to connect several offices within the same building or to connect different

floor of the building or in a working group or as a campus backbone
v. there are two types of Lan: wired and wireless

(1 marks for each answer, chose 3 answers only, total =3 marks)

Advantages of LAN:

i. hardware such as printer can be shared
ii. all the users work can be stored in a central place
iii. software can be share

28

iv. data can be shared
i. message can be sent to people working at other computers on the network

which can save time and paper.
(1 marks for each answer, chose 3 answers only, total =3 marks)

QUESTION 3
Sketch the configuration of Collision Sense Multiple Access /Collision Avoidance (CSMA/CA),
and Token Passing in Media Access Control (MAC) Protocol.
ANSWER
Carrier sense Multiple Access/Collusion Avoidence (CSMA/CA)

(3 marks)

Token Passing

(3 marks)
QUESTION 4
In addition to the wired network, various technologies exist which allow the transmission of
information between hosts without using cables. These are known as wireless technologies.
There are two types of services in wireless Local Area Network (LAN). With the aid of
diagram, interpret the TWO (2) services.

29

ANSWER
Basic service set

(4 marks)
i. BSS – The Basic Set is a set of all stations that can communicate with each other
ii. There are two types of BSS. Independent BSS (ad-hoc IBSS) and Infrastructure

BSS
iii. Every BSS has an identification (ID) called BSSID, which is the MAC address of the

access point (AP) servicing the BSS
iv. Ad-hoc (IBSS): with 802.11, it is posible to create an ad-hoc network of client

devices without a controlling access point (AP), the result is called an
independent basic service set (IBSS)
v. Infrstructure (BSS): starts communicates through AP. An AP acts as a master to
control the stations within that BSS

(1 mark for each point, total = 5 marks)

Extended Service set

(4 marks)

i. Made up of two or more BSSs with Aps.
ii. The BSSs are connected through a distribution system, which is a wired LAN

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iii. Distribution system connects the Aps in the BSSSs
iv. It allows for wider area of coverage
v. More user that the Basic Service Set (BSS)

(1 mark for each point, total =5 marks)

QUESTION 5
Media Access Control (MAC) is used to minimize collisions by determining turn of the station
to use the transmission medium or the channel. Three methods in MAC are Carrier Sense
Multiple Access/Collision Detection (CSMA/CD), Carrier Sense Multiple Access/Collision
Avoidance (CSMA/CA) and Token Passing. With the help of diagram interpret THREE (3) of
the MAC techniques and illustrate the MAC frame format for Standard Ethernet (IEEE 802.3)
of each frame.
ANSWER
CSMA/CD

i. every host has equal access to the wire and can place data on the wire when the
wire is free from traffic.

ii. In other words, devices are in listen-before-transmit carrier sense mode.
iii. When a device wants to place data on the wire for transmission, it will "sense" the

wire to find whether there is a signal already on the wire.
iv. If there is traffic already in the medium, the device will wait a random period of time

and "sense" again.
v. If there is no traffic (no signal in wire), the device will place the data in the medium.
vi. At the same time, the device is listening from the media, because the device wants

to ensure no other devices are transmitting at the same time.
(1 mark for each point, total= 5 marks)

(2 marks for carrier sense)

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(2 marks for collision detection)

(2 marks for jam signal)

(2 marks for random backoff)

CSMA/CA
i. For a Device to use a channel, it asks the AP by using a Request To Send (RTS)
message
ii. If channel is not in use, AP will send Clear To Send (CTS) message to all devices in the
BSS so they know the channel is being used
iii. Data is sent from STA
iv. After conversation is done, an Acknowledgement (ACK) is transmitted.
v. If the channel is not clear, the node/device waits for a randomly chosen period of
time, and then checks again to see if the channel is clear
vi. This period of time is called the backoff factor, and is counted down by a backoff
counter.
(1 mark for each point: total=6 marks)

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(1 mark for diagram, 1 mark for RTS, 1 mark untuk CTS, 1 mark for data, 1 mark for ACK,
total=5 marks)

TOKEN PASSING
i. The token is passed from station to station around the ring, always in the same
direction, in a predetermined sequence.
ii. A station must acquire the token in order to transmit data, and may only transmit
one frame (or use the token for a limited time) before releasing the token to the
next station.
iii. The data to be transmitted, together with any required control information, is added
to the token to create a data frame.
iv. The data frame is transmitted from station to station around the ring until it reaches
the destination device, which reads the data, marks the frame as having been
received and read, and transmits it to the next station.
v. When the frame arrives back at its point of origin, a new token is generated and is
transmitted to the next device on the ring.
(1 mark for each point, total = 5 marks)

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(8 marks)
(*choose 1 MAC only,total = 13 markah)

MAC frame format for Standard Ethernet (IEEE 802.3)

(1 mark for each field, total = 7 marks)

QUESTION 6
Interpret the importance of Media Access Control (MAC). Generalize the application in
detail based on THREE (3) types of MAC method used in Local Area Network (LAN).
ANSWER
Importance of MAC in LAN

i. MAC unique is used, which describe how devices share access to the LAN
ii. MAC layer protocol is the protocol that controls access to the physical transmission

medium on a LAN
iii. Provides a unique identification and access control for computers using Internet

Protocol (IP) network
(1 mark for each answer, choose 2 answers only , total = 2 marks)
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CHAPTER 5: PUBLIC DATA NETWORK

Public data network (PDN) is a network shared and accessed by users not belonging
to a single organization. A PDN is set up for public use. The Internet is an example of
a PDN. There are three types of networks; data network, value added network and
switching network.
A switched network is made up of a series of interconnected nodes called switches.
Switching is process to forward packets coming in from one port to a port leading
towards the destination.
Switching networks consists of three types; circuit switching, message switching and
packet switching.
Circuit switching network is a type of network where the communications between
end devices (nodes) must be set up before they can communicate. Meanwhile in
message switching network data is routed in its entirety from the source node to the
destination node, one hope at a time. During message routing, every intermediate
switch in the network stores the whole message and the packet switching network is
a network where the process of transmitting data in small units called as packets. A
small header containing signalling/addressing information about the source and
destination nodes is added to each such small data unit, to form packets.

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QUESTION 1
Explain TWO (2) types of Public Data Network.
ANSWER
Data Network

i. A data network is a system designed to transfer data from one network access point
to one other or more network access points via data switching, transmission lines,
and system controls.

ii. Data networks consist of communication systems such as circuit switches, leased
lines, and packet switching networks.
(2 marks)

Value Added Network (Van)
i. It is a private telecommunications network linking organisations in a supply chain
together, enabling them to share information and electronic documents.
ii. This network supports large organizations who are engaing in ebussiness
iii. A third party is hired to facilitate electronic data inerchange (EDI).
iv. This is an easy way to move data from one company to another.
(2 marks)

Packet Switching Network
i. Packet switching is a digital networking communications method that groups all
transmitted data into suitably sized blocks, called packets, which are transmitted via
a medium that may be shared by multiple simultaneous communication sessions.
(2 marks)
(*choose 2 answer only)

QUESTION 2
There are three types of common switching network namely as packet switching network,
message switching network and circuit switching network. Draw TWO (2) types of common
switching network from the three types mentioned above.
ANSWER
Packet Switching Network

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Message Switching Network ( 4 marks)
Circuit switching ( 4 marks)

( 4 marks)
(choose 2 types of switching only, total = 8 marks)

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QUESTION 3

Since 1970, packet switching has evolved substantially for digital data communications.
There are TWO (2) transmission methods involved in packet switching such as the Datagram
and Virtual Circuit. With the aid of a diagram, show the data transmission in Datagram.
ANSWER

(4 marks)
i. Each packet is treated independently
ii. The packet may take different paths to the destination
iii. The packet might arrive in a different sequence from the order in which they

were sent
iv. The packet may have to reordered at the destination

(1 marks for each point, total = 4 marks)
QUESTION 4
List THREE (3) common switching techniques used in Public Data Network. JUN 2018
ANSWER
3 types of common switching network:

i. Circuit switching
ii. Message switching
iii. Packet switching

(3 marks)

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QUESTION 5
With an aid of a diagram, explain the circuit switching operation.
ANSWER
circuit switching operation:

i. Circuit establishment
• A dedicated circuit is established between the source and the
destination through several intermediate switches.
(2 marks)

(2 marks)
ii. Data transfer

• Once the circuit is established, the sender starts to send data to the
receiver.
(2 marks)

(2 marks)

iii. Tear down
• Upon completion of the data transfer, the established connection is
terminated. All the nodes involved in the connection are notified to
release the resources that were reserved for the circuit.
(2 marks)

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(2 marks)
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REFFERENCES

Cisco System. (2005). CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy
Program), 3rd Edition. Cisco Press.
Forouzan, B.A. (2012). Data Communication and Networking (5th ed). Mc Graw Hill.
Jerry FitzGerald. Alan Dennis, Alexandra Durcikova (2014). Business Data Communications
and Networking. 12th Edition Willey.
Jeffrey S. Beasley, Gary M. Miller (2013). Modern Electronic Communication. 10th Edition.
Pearson/ Prentice Hall.
Lammle, T. (2011). CCNA Cisco Certified Network Associate Study Guide. 7th Edition. Wiley
Publishing.
Odom,W & Knott, T. (2006). Networking Basics CCNA 1 Companion Guide. Cisco Networking
Academy. Cisco Press
Tanenbaum. A.S. (2011). Computer Networks. 5th Edition. Prentice Hall.
Wayne T. (2004). Electronic Communication Systems: Fundamentals Through Advance . 6th
ed. Prentice Hall.Dean, T. (2015). Network + Guide to Networks.7th Edition. Cengage
Learning.
William Stallings (2015). Data and Computer Communications, International Edition. 10th
Edition. Pearson Education Limited
William Stallings, Thomas L. Case (2013). Business Data Communications: International
Edition. 7th Edition. Pearson Education Limited

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