GCSE Computer Science Paper
1 (Topics 3–4)
1.3 Computer networks, connections and
protocols
Networks Introduction
A network is a collection of connected computers that communicate by
sending data between themselves
Benefits of Networks -
Data exchange; data can be sent between computers without the need for
external storage
Resources like printers, scanners and internet connections can be shared
A network manager can manage all the other computers
They can update software, fix problems and help users by resetting
passwords
Network Performance -
Factors that affect the overall performance of a network:
Choice of hardware (e.g cabling)
Whether it is wired or wireless
Wired networks are faster and more reliable
Wireless performance depends on how well a computer can pick up the
signal but it is usually not better than a wired network
The topology of the network (how the computers are laid out and
connected)
Bandwidth (quantity of the data that can be transferred in a set amount of
time)
GCSE Computer Science Paper 1 (Topics 3–4) 1
, Bandwidth is shared between all the active users so the performance
can decrease if there are too many users
Types of Networks
Geographical Classifications of Networks -
Wide area network (WAN)
a collection of computers connected over a large geographical area
used by multinational organisations that have to connect to international
offices
usually rented from a large telecommunications company because they
are expensive to set up
The Internet is the largest WAN in the world
Local area network (LAN)
a collection of computers over a small geographical area
used by homes, schools, universities and small companies
is it set up and maintained by the organisation that uses it
Metropolitan area network (MAN)
A MAN is larger than a LAN but smaller than a WAN and typically covers
a relatively large area like a university campus, town or city
Personal area network (PAN)
A PAN is a personal network for an individual, such as a photographer
connecting a smartphone, desktop computer and printer together
Virtual Private Network (VPN)
A VPN allows for a secure and encrypted connection to a public
network like the internet. It is often used to protect an individual's
privacy by concealing their real location
GCSE Computer Science Paper 1 (Topics 3–4) 2
, Client-Server Model
Client-Server Model -
Computers take the role of either a central server or a client
The client can request a service from the server and the server will process
the request and send a response
The server provides services like storing files, printing and hosting a
website
This network is known as centralised since clients communicate with a
central server
Pros of the Client-Server Model -
Software and security updates can be managed centrally and affect all the
computers which is time-saving
Client machines can be monitored centrally so the admin can make sure
nobody breaks the terms and conditions of the network
For example, the administrator can retrieve lost files and recover lost
passwords
User files can be stored centrally making it easy to access from any
computer
Files can be shared easily
Cons of the Client-Server Model -
If the central server fails then the whole network can’t function
Servers can be targeted in cyber attacks such as Ransomware (prevents
you from accessing your device and the data stored on it, usually by
encrypting your files) and Denial of service (an attack meant to shut down a
machine or network, making it inaccessible to its intended users) attacks
Server hardware is expensive
GCSE Computer Science Paper 1 (Topics 3–4) 3
1 (Topics 3–4)
1.3 Computer networks, connections and
protocols
Networks Introduction
A network is a collection of connected computers that communicate by
sending data between themselves
Benefits of Networks -
Data exchange; data can be sent between computers without the need for
external storage
Resources like printers, scanners and internet connections can be shared
A network manager can manage all the other computers
They can update software, fix problems and help users by resetting
passwords
Network Performance -
Factors that affect the overall performance of a network:
Choice of hardware (e.g cabling)
Whether it is wired or wireless
Wired networks are faster and more reliable
Wireless performance depends on how well a computer can pick up the
signal but it is usually not better than a wired network
The topology of the network (how the computers are laid out and
connected)
Bandwidth (quantity of the data that can be transferred in a set amount of
time)
GCSE Computer Science Paper 1 (Topics 3–4) 1
, Bandwidth is shared between all the active users so the performance
can decrease if there are too many users
Types of Networks
Geographical Classifications of Networks -
Wide area network (WAN)
a collection of computers connected over a large geographical area
used by multinational organisations that have to connect to international
offices
usually rented from a large telecommunications company because they
are expensive to set up
The Internet is the largest WAN in the world
Local area network (LAN)
a collection of computers over a small geographical area
used by homes, schools, universities and small companies
is it set up and maintained by the organisation that uses it
Metropolitan area network (MAN)
A MAN is larger than a LAN but smaller than a WAN and typically covers
a relatively large area like a university campus, town or city
Personal area network (PAN)
A PAN is a personal network for an individual, such as a photographer
connecting a smartphone, desktop computer and printer together
Virtual Private Network (VPN)
A VPN allows for a secure and encrypted connection to a public
network like the internet. It is often used to protect an individual's
privacy by concealing their real location
GCSE Computer Science Paper 1 (Topics 3–4) 2
, Client-Server Model
Client-Server Model -
Computers take the role of either a central server or a client
The client can request a service from the server and the server will process
the request and send a response
The server provides services like storing files, printing and hosting a
website
This network is known as centralised since clients communicate with a
central server
Pros of the Client-Server Model -
Software and security updates can be managed centrally and affect all the
computers which is time-saving
Client machines can be monitored centrally so the admin can make sure
nobody breaks the terms and conditions of the network
For example, the administrator can retrieve lost files and recover lost
passwords
User files can be stored centrally making it easy to access from any
computer
Files can be shared easily
Cons of the Client-Server Model -
If the central server fails then the whole network can’t function
Servers can be targeted in cyber attacks such as Ransomware (prevents
you from accessing your device and the data stored on it, usually by
encrypting your files) and Denial of service (an attack meant to shut down a
machine or network, making it inaccessible to its intended users) attacks
Server hardware is expensive
GCSE Computer Science Paper 1 (Topics 3–4) 3
