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General Notes
24/05/17
1
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One advantage is that it allow s for communication between computers without having
to be physically somewhere else
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g
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One disadvantage is that it has a limited r ange, which means that you physically have to be in a
specific range to use it
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1 mark for stating an advantage/disadvantage
1 mark for expanding/explaining it
Advantages and disadvantages such as:
- Ease of use for mobile users
- Connectivity between different locations
- Reliability
- Cost
- Security
- Change in working patterns
- Health Issues
- Etc
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g
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[IB Answer]

Topic 3 Page 1

3
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1 Networks (9 hours)
Network Fundamentals
Data Transmission
Wireless Networking

Topic 3 Page 2

Network Fundamentals
Topic

Class Notes

3
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1 Identify different types of
networks

Organised Notes
A local area network (LAN) is a network that connects computers and other devices in a
relatively small area, typically a single building or a group of buildings
...
It powers a
large range of communication media
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An extranet is an controlled private network that has been opened to provide limited access to
a selection of users outside the organisation
...

Some characteristics of a P2P Network:
- No central server
- Resources are more widely available (storage, bandwidth, computing power)
- Redundancy/recovery
- Supports file sharing for collaborative work
3
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2 Outline the importance of
standards in the construction of
networks
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Standards are
necessary in networking in order to ensure that all network hardware communicates with the
other pieces of hardware without any issues
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Through the use of the OSI layer model if any standards change then the rules set out can
easily be changed without having to rewrite the complete rule set
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1
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• Translating real concepts into things that java
understands into things which C understands to
machine code (lower and lower level language)
...
The layers start with an input that then get translated into
lower and lower level language and eventually binary
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1
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A Virtual Private Network (VPN) is a secure network that uses the public internet for
communication, but has security features such as usernames, passwords and encryption, to
restrict access to a select group of users
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• Tunnelling protocols
• Allows a network user to access or provide a
network service that the underlying network does
not support or provide directly (Wikipedia)
• A tunneling protocol sends data to a network by
tunnelling the data from the client to the server
• Encapsulation of data to send somewhere else
• Hidden
• "Tunneling protocols allow data to be
encapsulated and therefore hidden when
travelling across a public network
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Topic 3 Page 3

Tunneling protocols allow data to be encapsulated and therefore hidden when travelling across
a public network
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Gateways restrict access to the network by requiring authentication
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The VPN server is the server

create a VPN
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" - Mr Madigan
• Gateway (client & server)
• Explain how gateways are used to create a VPN
• Gateways ensure that the data can travel from
one network to another by controlling the
amount of traffic that comes in and out of each
network
• "Gateways restrict access to the network by
requiring authentication
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1
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The VPN client is the software installed on the client's computer
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VPN requires:
• Internet connection
• A LAN that is connected to the internet
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• VPN client and server running on the lone machine and the original LAN

There are three types of VPN:
1
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(Point to Point)
2
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(Site to Site)
3
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Benefits of VPN:
- Resources such as files, printers and databases can be shared over the server
- VPN can reduce cost as VPN software is often freely available and open source
Limitations of VPN:
- Strong security measures are required as VPNs uses public networks
- Due to this, security measures need to be set up which requires knowledge of how to do
so in the first place, meaning that not everyone will be able to set up a VPN

Topic 3 Page 4

Data Transmission
Topic

Class Notes

3
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6 Define the terms: protocol, • e
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one of the ways of interpreting binary
data packet
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A data packet is a unit of data made into a single package that travels along a given network
path
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From PowerPoint:
Protocol - An internationally agreed set of rules to ensure transfer of data between devices
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3
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7 Explain why protocols are
necessary
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device without data lost
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ensure that data is read and transferred correctly
and that data is delivered in the correct language, in
order to make sure that the network understands it
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Computers, printer

3
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8 Explain why the speed of
data transmission across a
network can vary
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Time of day, distance, provider, and cable quality can affect data transmission
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g
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g
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g
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1
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It is also
transmitting across a network
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A file may not be able
to be sent if it's too big
...
g a video might need to
be compressed to send over email)
• Save time, resources, bandwidth
• Because the amount of data being sent is reduced
• Compression saves time and bandwidth because
less data is being sent

Compression reduces the amount of data being sent, which is necessary because it saves time,
resources and bandwidth due to less data being sent
...
1
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• 3 ways of data transmission
• WiMax - transmitted by microwaves
• ADSL
• Discrete - only 1 or 2
• Analogue can take on any values
• Consider these things about transmission media:
- Cost of transmission media
- Maintenance
- Reliability
- Strength
- Security
- Speed (bandwidth)
• Signal attenuates (degrading of signal)
...
[8 Marks]

A media is a means of communicating information
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1
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• Full use of bandwidth
• More secure
• Devices of different speed can communicate easily
• Resilient to communications hardware failure

Packet switching is the process by which files are broken down into smaller parts, called
'packets' in order for them to be sent with greater ease
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Each packet is built up of many different
parts, not only the data
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Security

Metal Conductor

Fibre Optic

Can be hard to maintain because
wiretapping is possible on metal
wires
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Reliability Low for the signal, it is vulnerable to High for the signal, it is immune to
electromagnetic interference
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Cost

Reasonable

Higher than copper wires

Speed

Limited

A lot higher than copper cabling, with
further increases anticipated
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1
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Health concerns
Advantages of wireless networks:
- The frequency of use affects visions, posture, general
- LANs can be set up without cabling
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Using your phone than rather do
Doesn't take space or time to lay the cables
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People can switch from router to
router automatically depending on which connection is best
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Many types are available on the market and they are affordable
Wireless networks affects social activities
Disadvantages of wireless networks:
Wireless networking affects working and studying patterns
- Interference with other devices on the network
- Has changed way people work, study, and communicate
- Limited Range
with one another
- Security issues (e
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hacking, stealing data)
- Health concerns (e
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general wellbeing, car crashes)

Organised Notes

3
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13 Describe the hardware
and software components of a
wireless network
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1
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Wifi vs Wimax vs Bluetooth vs 3G

From PowerPoint:
Hardware
- Modem to connect to the internet as per wired networks
- Wireless ‘Access Points’ (APs) are what directly communicates with the computers
in a wireless network
...

- Wireless Router takes the place of APs on home networks
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They contain a small antenna to send and receive electromagnetic
signals
...

- Wireless Antennas and Wireless Repeaters are used to amplify a wireless signal or
rebroadcast it
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- Firewall for security purposes
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- Software for Access Points to themselves connect to the wired network, and
translate between wired and wireless signals
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- Protocols:
Wireless Application Protocol (WAP)
Dynamic Host Configuration Protocol (DHCP)
- Browsers and other user applications are used on the networks
...
)

Reliability

Depends on
proximity to
APs

?

Very
reliable at
close
range

Reliable in the city

Speed
Up to 300
(bandwidth) Mbps

> 100
Mbps

25 Mbps

> 200 kbps

Security *all

Similar
security
measures
required

Same as
wifi

Easily
'hacked'
but only if
within
range

More secure than public wifi

~30m
Up to 100m
outdoors

~50km

~10m

~80km

easily
intercepted

Range

3
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15 Describe the different
methods of network security
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The receiving device (which can be the WAP) should know an
use the same 'key' to decrypt the packet
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Limitation:
- Keys must be shared before they can be used
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Asymmetric Key Encryption (Public Key Encryption)
This uses a different key for encryption and decryption
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The sender
cannot decrypt the message once encrypted
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This makes it more secure
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3
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16 Evaluate the advantages
and disadvantages of each
method of network security
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method of network security
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Not vulnerable
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Anyone can access the network
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Prevents
unauthorised access
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Takes some time to enter password
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May slow down device
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May slow down device or network
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the settings of the wireless Takes some time to enter password
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Switching On /
Off the Wireless
Network

Complete security while off
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Router firewall

Blocks unauthorised traffic
from the wired connection
to the net
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Experienced
to general population
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Limit access to
wireless devices
by MAC address

Only trusted devices can
access the network
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Hackers
can still get around this by ‘sniffing’ the
list of allowed devices and ‘spoofing’
their MAC address
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Outdated and vulnerable to cracking
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Strong
encryption
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Wireless
Easy to use
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Only works with
certified devices
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Prevent Physical Network traffic can no
Access (Shielding) longer be intercepted
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Encryption
Software

Takes some time
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IB Questions
Outline the need for protocols in network communication
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[4 marks]
a) Define the term server
b) Identify the different clients in this network
c) i
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ii
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[2 marks]

Topic 3 Page 8



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