European Computer Driving
Licence
Module 1 – Concepts of IT
Chapter 1.4 Information Networks
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Local Area Network
Z Computers which are linked by cabling in the same room or
building
Z A server controls the network and stores data which is used by
other users on the network (clients),
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Networks
Z Advantages
,
,
,
,
Z Disadvantages
Printers, scanners etc can
be shared
Work is stored on the server
and can be accessed from
any of the client computers
Users can communicate and
exchange data
Software is loaded once
onto the server rather than
on individual computers
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,
,
Security measures are
needed to stop users
accessing programs and
data
Can be complicated to set
up and requires support
from skilled technicians
Faults affecting the server
will affect the client
computers
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Wide Area Networks
Z A WAN connects computers
in different geographical
areas
Z These are connected via the
telephone system
Z Used by multinational
companies to communicate
between different countries
Z The world’s largest WAN is
the Internet!
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The Telephone Network in
Computing
Z A modem is required for a computer to communicate over
telephone lines
Z Data is converted from digital to analogue and then back again
Z The speed at which data is transmitted and/or received is
measured in bits per second
Z The current standard is 56,000 bits per second
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Public Switched Telephone
Network
Z PSTN for short!
Z The international telephone
system used for making dayto-day telephone calls
Z It is the main reason why
computers have become so
popular in recent years!
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Integrated Services Digital Network
Z ISDN for short
Z Has a greater range of
frequencies than PSTN
Z At least as twice as fast as
PSTN
Z Typical transfer rate of
128,000 bits per second
Z Data is transmitted
simultaneously
Z Special connection and
modem required
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Asymmetric Digital Subscriber Line
Z ADSL for short
Z Uses telephone lines to transmit
data at very fast speeds
(512,000 bits per second)
Z ADSL modem and splitters
required to separate telephone
signal from the ADSL signal
Z You can still make telephone
calls when surfing the web!
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The Internet
Z Huge network of computers connected together
(including yours)
Z Minimum requirements are a 486 processor with
Windows 95, modem, an account with an Internet
Service Provider (ISP) and a telephone line
Z The ISP provides access to the Internet through their
servers
Z Many ISPs do not charge as users will normally pay
for the access via their telephone bills
Z Many ISPs offer flat-rate access at fixed cost
(e.g. AOL)
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E-Commerce
Z Growth of the Internet in the last
few years has been phenomenal
Z Virtually any organisation has
their own web site
Z Virtually anything can be bought
or sold over the Internet
Z All banks offer online banking –
you can access your bank
account 24/7
Z The Internet is available 365
days a year – it never closes!
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Purchasing Over The Internet
Z You have to enter your
name, address and
credit/debit card details to
purchase goods/services
Z Most sites will offer a secure
site which will scramble your
details so it can’t be
intercepted by thieves
Z Secure sites will start with the
prefix https:// - look out for
the padlock symbol at the
bottom of your screen
Z You have the same
consumer rights as buying
from a shop
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Purchasing Over The Internet
Z Advantages
,
,
,
,
Z Disadvantages
You can shop 24 hours a
day, 7 days a week
You can shop from the
comfort of your own home
You can surf the web to find
the best bargains
Many dealers will offer
discounted prices for
shopping online
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,
,
,
You cannot see or try goods
before purchasing
You may have to pay extra
for delivery
You cannot speak to a
person for sales advice
There is some degree of risk
giving out your debit/credit
card details over the Internet
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Alternative Payment Methods
Z You can use online services
to send money, as opposed
to sending cheques
Z NOCHEX
(www.nochex.co.uk) lets you
send and receive money
from anyone with an email
address and a debit card
Z Paypal (www.paypal.com)
offers a similar service
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E-mail
Z By far the most popular use
of the Internet
Z E-mail messages arrive
almost instantaneously,
anywhere in the world
Z The same message can be
sent to more than one person
at the same time
Z It is very easy to reply to and
forward e-mail messages
Z Documents or photos can be
sent as attachments
Z E-mail software is required or
you can access webmail
providers online (e.g.
Hotmail, Yahoo, Lycos etc)
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Intranets and Extranets
Z Intranet is similar to the
Internet but is internal to an
organisation
Z Users access the Intranet
through a user name and
password
Z Enables users to share
information and communicate
via electronic messaging
Z An Extranet can be accessed
from outside the Intranet by
authorised users via a user
name and password
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