What is a computer network?
A network connects several nodes or networking
devices together. This allows sharing of
resources such as printers, storage
Different Types of Networks
• LAN (Local Area Network)
Also includes WLAN (Wireless LAN)
In this presentation we will only be looking at LAN, WAN and
LAN (Local Area Network)
• It is a small network with a maximum coverage
of about a few buildings.
• Allows sharing of printers, medium sized
• Mainly used in offices and schools.
• Advantages: sharing of resources, communication
increases, controlled by an administrator.
• Disadvantages: malware threat, queues, slower access
to external networks, lesser data security compared
to stand alone computers, if there is a break-down of
a node then the network will brake.
Topologies of LAN
• Bus Topology
• Ring Topology
• Star Topology
Computers are connected to a
Data moves towards the
A Terminator is often used
here. It is a device used at the
ends of the main line to avoid
signal bounce which can lead to
Advantages: easy to add new
node, entire network will not get
affected with the failure of one
node, less cables required, cost
Disadvantages: if main line
malfunctions the entire network
will fail, more nodes will decrease
speed, difficult to isolate a fault
on a particular device or computer.
It’s a chain of nodes
cabled together to form
Each computer receives
data only relevant to it as
each computer has a
efficiently even with
heavy data load, suitable
for larger networks.
can fail of there is a
cable fault, addition of
new node is difficult as it
has to be placed between
Each node is connected to
each other by a hub or a
Every node has its own
connection to the hub.
Advantages: if one node fails
the entire network is not
affected, easy to work on a
faulty node and isolating
it, network can be easily
Disadvantage: break down of
hub will lead into full
WAN(Wide Area Network)
A network over a large area such as
cities, countries, etc.
Connected by a router or a modem
Expensive because of additional hardware
and operating system
WLAN (Wireless Local Area Network)
Communication is made over short distances with either
radio or infrared signals instead of cables.
Ranges of different signals
• Radio: 30-50 metres
• Infrared: 1-2 metres
A device called Access Point is connected to such
Advantages: all computers can access that same
material, less cabling, flexibility, adding new device is
Disadvantages: big security threat if network is
unprotected, signals can be interfered with, transfer rate
Modem (Modulator Demodulator): converts digital signals
in to analogue signals (modulation) and vice versa
Network Hub: connects numbers of nodes from where it
receives of one device and sends it to all devices.
Switches: connects numbers of nodes from where it
receives data and sends it to the relevant node.
Routers: used to connect networks together and to the