Pass ECDL4 1

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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NetworksZ Advantages

, 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

Z Disadvantages, 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 againZ The speed at which data is transmitted and/or received is

measured in bits per secondZ 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 day-to-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 shortZ Has a greater range of

frequencies than PSTNZ At least as twice as fast as

PSTNZ Typical transfer rate of

128,000 bits per secondZ Data is transmitted

simultaneouslyZ Special connection and

modem required

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Asymmetric Digital Subscriber Line

Z ADSL for shortZ 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-CommerceZ Growth of the Internet in the last

few years has been phenomenalZ Virtually any organisation has

their own web siteZ Virtually anything can be bought

or sold over the InternetZ 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 InternetZ Advantages

, 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

Z Disadvantages, 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