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Computers,
part of your
life
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MODULE 2.1
Local area networks
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Contents
 What is a network?
 Basic components of a
network
 Advantages and
disadvantages of a LAN and
WLAN
 Basic network security
 Ethical use of networks
 Test and improve your
knowledge
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A NETWORK
is a collection of computers or
other computing devices that are
connected by some sort of
communication media (either via
cable or wirelessly) to allow users
to share software, hardware, data
and information, and to
communicate.
What is a network?
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What is a network? LAN
 A local area network (LAN) is a network connecting
computers in a small area such as a school, university
campus or company offices in one building.
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What is a network? LAN
A local area network (LAN)
• is a network connecting computers in a small area
such as a school, university campus or company offices
in one building.
A wireless LAN (WLAN)
• is a LAN which uses wireless (radio waves) to
communicate rather than cables.
An intranet
• is an organisation’s private network and is an Internet-
like environment consisting of web pages relating to
the organisation’s business.
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Computers and peripherals
Workstations
desktop
compu
ters
laptops iPads
Smart
phones
Server
file
server
e-mail
servers
Internet
or proxy
servers
print
servers
Basic components of a network:
Hardware
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Hardware
Network interface controller
allow the computer
to communicate with
the network
built into the
motherboard of all
computers
Switch
hardware device
used to connect
computers in a
network so that
communication can
occur
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9
Network
Interface
Controller
Switch

Data transmission speed
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Data transmission speed is the rate at which data is
transferred over the media used.
 Cabled networks: 10/100/1000 – this refers to
the data transmission speed that the NIC can
support – 10 Mbps/100Mbps/1000Mbps.
 Multiple speeds = max speed depends one type of
cabling and equipment used in network. NIC
automatically detects and operates at the fastest
speed.

Data transmission speed
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 Wireless NIC: 802.11 (g or n) – indicates speed that
wireless network is capable of.
 g = 10Mbps and n = 50Mbps.
 Mix of wireless equipment at different speeds =
speed is determined by slowest component
Data transmission over WLAN is slower than over
(cabled) LAN

Communication media
Wired media
Cables
UTP
(Unshielded
Twisted Pair)
Fibre optic cable
Wireless
wireless access
points
wireless enabled
/ wireless
adaptor
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13
Unshielded Twisted pair VS. Fibre Optic Cable

Network operating software
Software that controls all the
communication and security in a network.
Most operating systems such as Windows
7.0 have built-in networking capabilities.
For larger networks, specialised ‘Server’
editions of the operating system need to be
installed on the servers
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How do
you know
that you
are
connected
to a
network?
 Presence of extra (logical)
drives such as U:, V: and T:
which are simply folders on a
server that are appearing and
acting as drives.
 Presence of other computers in
My Network Places.
 Access to devices such as
printers not directly attached to
the computer is possible.
 Indicator showing network
activity in the system tray.
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Advantages and disadvantages
of a LAN and WLAN
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Advantages
 Files stored on central
computer (file server)
users access from any
computer in the network.
 Files transferred easily
without the use of devices.
 Software shared by
many users.
 Hardware shared by
many users.
 Security in the network
can be controlled.
 A single Internet
connection shared by
many users.
 Software kept up to date
using a network.
 Software which allows you
to demonstrate or
broadcast to all the
computers in a classroom.
 Internet access
monitored and controlled.
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Advantages - Wireless
 Easy to add or move
computers as the network
points are not fixed.
 Installation easier than
with a cabled LAN.
 It is easy to provide
network connectivity in
areas where it is difficult to
lay a cable.
 Adds mobility for users
with mobile devices such as
laptops and smartphones.
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Disadvantages
 A LAN/WLAN can be
expensive to install and
maintain.
 A network
administrator is often
necessary to manage the
network.
 Network security must
be maintained to ensure
that the data on the
network is kept secure.
 If the file server is faulty,
no one can access their
files.
 Security can be
compromised if the WLAN is
not configured correctly to
prevent hacking.
 Unauthorised users may
also make use of your Internet
connection- costing money.
 Performance can decrease
as the number of computers
connected increases.
 Signal could get lost or
interfered with due to
electronic or electrical
interference.
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Network security refers to policies
(rules) put in place to ensure the
security of a network by preventing
unauthorised access to information
and misuse of the computer network.
Basic network security
• An organisation would not want all their employees to have
access to files to do with the salaries of the employees.
• In a school situation, it is important that pupils do not have
access to tests and exams before they are written or that they
are not able to change their term’s results.
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When working in a network
environment:
 You use a username and password to gain access to
the network and its resources.
 You will be issued with a username.
 Choose a password that will only be known to you.
 You will be held responsible for any actions done on
the network under your username and password.
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Example of a ‘good’,
secure password:
Q1w2E3R4t%y

A few rules to follow
 Choose password that is at least 8 characters long.
 The password should contain a mixture of upper and
lowercase letter, numbers and special characters.
 You should not use anything else that is easy to guess
about you. In fact meaningless passwords are the
best.
 Be careful of using passwords that follow a pattern
on the keyboard such as ‘asdf’ or ‘1234’ as these are
also easy to guess.
 You should change your password at least every 2
months.
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Whenever people are interacting and
sharing resources, there is a need
for acceptable, ethical practices.
Most organisations, including
schools, make use of an acceptable
use policy (AUP) to outline the rights
and responsibilities of its users,
especially in networked
environments.
Ethical use of networks
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An Acceptable Use Policy (AUP) needs to be
frequently updated and is put in place to
 clearly list what the users are permitted and not
permitted to do in order to protect them when they are
using computers and when they are online.
 include basic netiquette rules and responsible
computer usage, as well as any other restrictions the
organisation might feel is necessary to implement such
as restrictions related to Internet usage.
 serve as a contract between the organisation and
the user summarising what they can and can’t do as
well as possible consequences of not complying with the
policy.
 put the duty of using the network in a responsible and
ethical way, on the user.
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What should be included in an AUP? (1/2)
 A code of conduct with respect to
 ethical, legal and safe use
 privacy of other users
 forms of online communication
 restrictions on the amount of data and
information downloaded from the Internet
 accessing sites with objectionable/offensive
material as defined by the laws of the country
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What should be included in an AUP?(2/2)
 Details on when and where portable storage devices
may be used
 Details of restrictions about installing any hardware or
software
 Procedures to follow if users find they are victims of
identity theft, malware such as viruses, cyber bullying or
cyber stalking
 Hints to avoid plagiarism and the breaking of copyright
law
 Clear consequences of violating conditions spelt out
in the AUP
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Test and improve your
knowledge
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Overview of module
What is ?
Network
LAN
WLAN
Basic
components
Hardware:
• Computers
• Peripherals
• NIC
• Switch
Communicati
on media:
• Wired
• Wireless
Network
operating
software
Advantages
and
Disadvantages
LAN/WLAN
Network
security
Passwords
Ethical use
of networks
AUP
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Important terms and concepts
Intranet
Local area
network
(LAN)
Network
Network
interface
controller
(NIC)
Network
operating
software
Network
security
Server Switch
Wireless local
area network
(WLAN)
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