COMPUTER NETWORKS
• What is a Network?
• A network is two or more computers, or other electronic devices, connected together so
that they can exchange data, share resources and communicate .
For example a network allows computers to share files, users to message each other, a
whole room of computers to share a single printer, etc.
Network connections between computers are typically created using cables (wires).
However, connections can be created using radio signals (wireless / wi-fi), telephone
lines (and modems) or even, for very long distances, via satellite links.
WHY USE NETWORKS?
Using a computer connected to a network allows us to…

Easily share files and data

Share resources such as printers and Internet connections

Communicate with other network users (e-mail, instant messaging, video-conferencing,
etc.)

Store data centrally (using a file server) for ease of access and back-up
• Keep all of our settings centrally so we can use any workstation
WHY USE NETWORKS?
In particular, if we use a computer connected to The Internet, we can:

Make use of on-line services such as shopping (e-commerce) or banking

Get access to a huge range of information for research

Access different forms of entertainment (games, video, etc.)

Join on-line communities (e.g. Instagram, Facebook, etc.)
NETWORKS
Internet protocol (IP) and Media Access Control Address (MAC)
WHAT IS AN IP ADDRESS?
• IS a unique 32 bit number assigned for particular
session
• E.G. 192.168.1.15
MEDIA ACCESS CONTROL (MAC) ADDRESS
• What is a MAC address?
• A MAC address is a unique number that identifies a
device connected to the internet
WI-FI AND BLUETOOTH
• How does Wi-fi work?
• How does Bluetooth work?
BLUETOOTH VS WI-FI
Feature
Bluetooth
WI-FI
Transmission frequency used
2.4 GHZ
2.4, 3.6, 5.0 GHz
Data transfer rate (maximum)
25 Mbits/second ( 3.1 Mbytes/
31 Mbytes/Second
Maximum effective range
(metres)
30m
100m
Maximum number of devices
connected
Up to 7
Depending on Router used
Type of data transmission security Key matching encryption
WEP (wireless equivalent
privacy) and WPA (Wi-Fi
protected access)
INTERNET, INTRANET & EXTRANET
• INTRANET
• EXTRANET
• INTERNET
LESSON NOTES
IP AND MAC ADDRESSES
• Each device on the internet is given a unique address known as
its internet protocol (IP) address. This is a 32-bit number that is
usually written in the form: 109.108.158.1.
• A home computer is given an IP address when it connects to the
internet. This is assigned by the ISP and is unique for that
particular internet session. The only IP address that remain fairly
unchanged are the web servers. An IP address can be used
instead of typing in the full URL; for example, http://109.108.158.1
DIFFERENCE BETWEEN IP AND MAC
ADDRESSES
• A Media Access Control (MAC) address is a unique number that
identifies a device connected to the internet. Whereas an Internet
Protocol (IP) address gives the location of a device on the
internet.
WIFI AND BLUETOOTH
Both Wi-Fi and Bluetooth offer wireless communication between
devices. They both use radio frequencies as the carrier of data
transmission.
Wi-Fi
A wireless transmitter (WAP) receives information from a network
via its connection (e.g. a broadband connection if the internet is
used). This transmitter converts the received information into radio
waves and then transmits them.
CLASS EXERCISE
1. What is the difference between a LAN and a WAN
2. Give one advantage and two disadvantages of using
Bluetooth rather than Wi-Fi
3. Give one two advantages and one disadvantage of a
company connecting their computers to the internet
4. Describe how a mobile device can transfer a music file
to another device using Bluetooth
CLASS EXERCISE
• 1. Give two benefits of using a local area network
[2]
• Give one difference between a local area network (LAN) and a wide area
network (WAN)
• Describe two advantages and two disadvantages in a company using a
computer network [4]
• Give two advantages and two disadvantages of using a WLAN
• Explain the difference between the terms internet and intranet
• Describe what is meant by a web browser software