This document discusses networks, including LANs and WANs. It defines a LAN as a local network within a building that connects computers, and typically includes a file server, terminals, and print server connected with cables. A WAN connects computers over long distances, sometimes between countries, and requires modems. There are three main network topologies - the ring, bus, and star - each with their own advantages and disadvantages. Network security involves physical, access, and data security measures.

1. Networks
By the end of this session, you will:
• Define and describe a LAN and WAN.
• Understand the hardware required.
• Know the 3 LAN topologies.

2. Networks
• What is a Network?
• What is a LAN? What hardware do you need to
make one?
• What is a WAN? What hardware do you need
to make one?
• What are the advantages and disadvantages
of a network?
• Draw a star, ring and bus network – give
advantages and disadvantages of each.

3. Networks
A network is two or
more computers
Computer 1
connected together so
they can communicate
which each other.
There are 2
Computer 2 main types of
network…

4. Networks: LANs
LAN LANs are networks
stands that are found where
for: computers within a
building need to
LOCAL communicate.
AREA
NETWORK
They are Small and Local!

5. Networks: LANs
What hardware do you need for a LAN network?
•File Server : Runs software, stores files.
•Terminals : Workstations that give network access.
•Print Server : Queues up all print jobs from users in network.
•Cables (wire/optic) : Sends data.

6. Networks: WANs
WAN WANs are networks
stands that are found where
for: computers in
different areas or
WIDE countries need to
AREA communicate.
NETWORK
They are long range and not local!

7. Networks: WANs
What extra hardware do you need for a WAN
network?
•Modems : To connect up to a telephone system (instead of cable).

8. Networks: Ad/Disad
Some advantages of a network
are:
• Resources (Hardware and Software) can be shared.
• Allows more effective communication between users.
• Networks are cheaper than “stand-alone PCs.”
• Information held on the network can be accessed by all
users with authorised access.

9. Networks: Ad/Disad
Some disadvantages of a network
are:
• The set-up and maintenance costs can be expensive.
• A fault with the network server can cause difficulties
with the organisation.
• Networks need security measures to restrict access to
users.
• WANs are vulnerable to hackers and viruses.

10. Networks
As well as knowing the advantages and
disadvantages of a network…
You need to know the advantages and
disadvantages of 3 network topologies…

11. Network Topologies
There are 3 main types of network
topologies:
The Ring The Bus The
Networ Networ Star
k k Networ

12. Network Topologies
The Ring
Network: Computers are
connected
together to form a
ring shape so that
none of them is
more important
than any of the
others.

13. Network Topologies
The Ring
Network:
Advantages: Disadvantages:
•They are cheap to •If there are a lot of
expand. users on the network, it
could slow down as all
•The data flows around
the data is sent along a
the network in one
single line.
direction so it is fast.
•If one computer in the
•There is no reliance on
ring stops working, the
a central computer.
whole network stops.

14. Network Topologies
The Bus (or line) Network:
Computers are
connected like bus
stops on a main
road. None of
them is more
important than
any of the others.

15. Network Topologies
The Bus (Line) Network:
Advantages: Disadvantages:
•It is cheap as it uses •With a lot of users, the
the least amount of network will be slow as
cable. data has to travel
through the same central
•More computers can be
cable.
added without
disruption. •Failure of the central
cable will stop the
network from working.

16. Network Topologies
The Star Network:
Computers are
connected like a
star to a central
computer such as
a mainframe.
This is also called
the “host”
computer.

17. Network Topologies
The Star Network:
Advantages: Disadvantages:
•If a cable fails, it will •It is more expensive as
only affect one it uses the most cabling.
workstation.
•Failure of the central
•More computers can be computer will stop the
added without network from working.
disruption.

18. Networks: Security
Because networks are almost vital to an
organisation’s daily activities, they must
be kept safe and secure…
There are 3 main types of network security…
Physical, Access and Data.

19. Networks: Security
Physical security means that
the hardware of the network
is protected from theft and
kept safe.

20. Networks: Security
Access security
means that there is
a limit to the
amount of access a
user has to the
information held on
the network.

21. Networks: Security
Data security means that
there are measures taken to
prevent the loss of data
held on the system.