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Amy Cole 10T

Section 2.4: Computer networks

(a) Network equipment
a. Describe a router and its purpose
A router is a network device that connects together two or more networks.

A common use of a router is to join a home or business network (LAN) to the Internet (WAN).


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Amy Cole 10T

Server(s) to manage network functions such as network security, network file storage, shared
resources (such as printers)

You would need to organise some other things:

Set up an account with an Internet Service Provider (ISP)
Get an Internet connection installed from the ISP to your location

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Amy Cole 10T

A hub is a `dumb' device: if it receives a message, it sends it to every computer on the network. This means
that hubbased networks are not very secure everyone can listen in to communications.

Hubs are pretty much obsolete now (you can't buy them any more),…

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Amy Cole 10T

ii. Wireless Local Area Network
A wireless LAN (WLAN) is a LAN that uses radio signals (WiFi) to connect computers instead of cables.

At the centre of the WLAN is a wireless switch or router a small box with one or two antennas sticking out
the back…

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Amy Cole 10T

b. Describe the difference between LANs, WLANs and WANs, identifying their main characteristics

c. Describe the characteristics and purpose of common network environments, such as intranets
and the internet

The Internet is a worldwide network that has grown and evolved from an experimental network (ARPANet)
created by…

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Amy Cole 10T

The Internet connects millions of people, and thousands of businesses, governments, schools, universities and
other organisations.

What Can We Use the Internet For?

The Internet provides the network connections that link computers together. There are many ways that we
can use these connections:

View web pages on…

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Amy Cole 10T

Communicate with other network users (email, instant messaging, videoconferencing, etc.)
Store data centrally (using a file server) for ease of access and backup
Keep all of our settings centrally so we can use any workstation

In particular, if we use a computer connected to The Internet, we…

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Amy Cole 10T

Video conferencing Can be long distance. Need a strong internet connection.
You can see the other people. Need additional hardware such as webcams,
Done in real time. large monitors, microphones and speakers.
Can see reactions, facial expressions and There can be lag.
body language. The sound and…

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Amy Cole 10T

For this to be effective passwords must be chosen that are not easy to guess. Passwords should be a random
combination of lowercase letters, uppercase letters and numbers (and symbols if this is allowed):

`Weak' passwords: password, 123456, david, 27dec1992
`Strong' passwords: s63gRdd1, G66ew$dQ, gdr298783X

Some computer…

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Amy Cole 10T

Now that Bob has a copy of the key, each time Alice needs to send him a message she starts by encrypting it
using special encryption software and the secret key.

The encrypted message now looks like a jumble of random letters and numbers.

Alice then sends…


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