Computer SystemsComputer Systems

NetworkingNetworking

What is a NetworkWhat is a Network

A network can be described as a number A network can be described as a number of computers that are interconnected, of computers that are interconnected, allowing the sharing of data and allowing the sharing of data and peripherals. There are two types of peripherals. There are two types of networks:networks:

LANLAN WANWAN

Local Area Network (LAN)Local Area Network (LAN)LAN’s provide networking capability to a group of LAN’s provide networking capability to a group of

computers in close proximity to each other, computers in close proximity to each other, such as in an office building, school or at such as in an office building, school or at home.home.

LAN’s are useful for sharing resources such as LAN’s are useful for sharing resources such as files, printers, games etc.files, printers, games etc.

A LAN after connects to other LAN’s and to the A LAN after connects to other LAN’s and to the Internet to allow global e-mailing.Internet to allow global e-mailing.

Wide Area Networks Wide Area Networks (WAN)(WAN)

A WAN spans a large geographic area, A WAN spans a large geographic area, such as a region (west Lothian), city such as a region (west Lothian), city (Edinburgh) and country (Scotland).(Edinburgh) and country (Scotland).

WAN’s often connect multiple smaller WAN’s often connect multiple smaller networks, such as LAN’s (schools all networks, such as LAN’s (schools all connected)connected)

InternetInternet

The internet is a global network where The internet is a global network where many LAN’s and WAN’s are many LAN’s and WAN’s are interconnected.interconnected.

Advantages of Advantages of Networking Networking

You can share data, files and You can share data, files and equipment.equipment.

Permits ‘Live’ ChatPermits ‘Live’ Chat Allows users to email each otherAllows users to email each other Password securityPassword security Assess Levels Assess Levels

Transmission MediaTransmission MediaIn order to be able to connect to the internet, or In order to be able to connect to the internet, or

connect to a server it is necessary to have connect to a server it is necessary to have hardware. The most common ishardware. The most common is

Twisted pairTwisted pair – a type of cable that – a type of cable that plugs plugs into the computerinto the computer

Wireless connectionWireless connection – your machine – your machine requires a wireless network card.requires a wireless network card.

Development of computer Development of computer networksnetworks

The main factors leading to the The main factors leading to the development of computer networks are:development of computer networks are:

Shared access to expensive equipmentShared access to expensive equipment Demand for up-to-date informationDemand for up-to-date information Falling costs of communication servicesFalling costs of communication services

Client/Server NetworksClient/Server Networks

The central computer (the server) acts as a The central computer (the server) acts as a resource for the others. It stores the programs resource for the others. It stores the programs and data files that the client (computers in main and data files that the client (computers in main room) accesses. room) accesses.

Users will normally log on to the network with a Users will normally log on to the network with a user name and password.user name and password.

The server will normally have a faster processor, The server will normally have a faster processor, more RAM and a greater amount of backing more RAM and a greater amount of backing storage (hard drive) than the computers on the storage (hard drive) than the computers on the network.network.

Network BenefitsNetwork Benefits

SecuritySecurity

Tampering with programs and files is Tampering with programs and files is prevented through restricted access prevented through restricted access rights.rights.

Personal work is saved in private spaces Personal work is saved in private spaces on hard disks that are password on hard disks that are password protected.protected.

Communication:Communication:

Data files, programs and peripherals Data files, programs and peripherals devices can be shareddevices can be shared

Communication is improved via Communication is improved via e-mail/chat/bulletin boardse-mail/chat/bulletin boards

Management:Management:

Centralised back-up of filesCentralised back-up of files Stations can be managed remotelyStations can be managed remotely

World Wide Web (WWW)World Wide Web (WWW)

To access the information on the www you To access the information on the www you need a browser application, AOL, BT need a browser application, AOL, BT and Internet Explorer are browsers.and Internet Explorer are browsers.

The www is made up of web pages which The www is made up of web pages which usually contain text, images and sound.usually contain text, images and sound.

HyperlinksHyperlinks

A hyperlink on a page normally identified in A hyperlink on a page normally identified in blue and underlined allows any page on blue and underlined allows any page on the web to connect to any other pagethe web to connect to any other page

www.wikkispaces.org.ukwww.wikkispaces.org.uk

Search EnginesSearch Engines

Websites such as Yahoo and Google Websites such as Yahoo and Google include a search engine that regularly include a search engine that regularly runs programs called runs programs called web crawlersweb crawlers to to gather information about what pages are gather information about what pages are on the interneton the internet

When you enter a search you are When you enter a search you are searching a database for words that searching a database for words that match your entry.match your entry.

Address BookAddress Book

When you are in the habit of sending e-When you are in the habit of sending e-mails regularly to the same people it is a mails regularly to the same people it is a good idea to store their e-mail addresses good idea to store their e-mail addresses in an electronic address book.in an electronic address book.

Mailing ListsMailing Lists

When your contacts increases you may When your contacts increases you may sometimes want to send the same sometimes want to send the same message to several people.message to several people.

This can be done by creating a MAILING This can be done by creating a MAILING LIST, you may want to have a list for LIST, you may want to have a list for friends, and another for familyfriends, and another for family

LegislationLegislation

The law has struggled to keep up with the The law has struggled to keep up with the rapid pace of change that the internet rapid pace of change that the internet has brought to society and consequently has brought to society and consequently new legislation has had to be introduced. new legislation has had to be introduced.

The following are three of the most The following are three of the most common laws concerning the use of common laws concerning the use of electronic information and access to electronic information and access to networksnetworks

LegistlationLegistlation

Computer Misuse ActComputer Misuse Act

Copyright Designs and Patents Copyright Designs and Patents ActAct

Data Protection Act.Data Protection Act.

Computer Misuse ActComputer Misuse ActThis act was introduced to secure computer This act was introduced to secure computer

material against unauthorised access or material against unauthorised access or modification. The three categories established modification. The three categories established are:are:

Unauthorised access (HACKING) including Unauthorised access (HACKING) including illicit copying of software.illicit copying of software.

The circulation of ‘infected’ material (viruses)The circulation of ‘infected’ material (viruses) Intentional destruction of software or data.Intentional destruction of software or data.

Copyright Designs and Copyright Designs and Patents ActPatents Act

Any uploading or downloading of Any uploading or downloading of information through on-line technologies information through on-line technologies that is not authorised by the copyright that is not authorised by the copyright owner is deemed to be an intrusion of owner is deemed to be an intrusion of their rightstheir rights

Data Protection ActData Protection Act

If someone holds data electronically about If someone holds data electronically about an individuals, then that individual has an individuals, then that individual has the following rightsthe following rights

To view a copy of the data being held on To view a copy of the data being held on themthem

To have any inaccurate data correctedTo have any inaccurate data corrected To prevent receiving junk mail To prevent receiving junk mail

Finished NetworksFinished Networks

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(Computer Software)(Computer Software)