Computer Systems Networking

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

Local Area Network (LAN) LAN’s provide networking capability to a group of computers in close proximity to each other, such as in an office building, school or at home. LAN’s are useful for sharing resources such as files, printers, games etc. A LAN after connects to other LAN’s and to the Internet to allow global ing.

Wide Area Networks (WAN) A WAN spans a large geographic area, such as a region (west Lothian), city (Edinburgh) and country (Scotland). WAN’s often connect multiple smaller networks, such as LAN’s (schools all connected)

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

Advantages of Networking  You can share data, files and equipment.  Permits ‘Live’ Chat  Allows users to each other  Password security  Assess Levels

Transmission Media In order to be able to connect to the internet, or connect to a server it is necessary to have hardware. The most common is Twisted pair – a type of cable that plugs into the computer Wireless connection – your machine requires a wireless network card.

Development of computer networks The main factors leading to the development of computer networks are:  Shared access to expensive equipment  Demand for up-to-date information  Falling costs of communication services

Client/Server Networks

The central computer (the server) acts as a resource for the others. It stores the programs and data files that the client (computers in main room) accesses. Users will normally log on to the network with a user name and password. The server will normally have a faster processor, more RAM and a greater amount of backing storage (hard drive) than the computers on the network.

Network Benefits Security  Tampering with programs and files is prevented through restricted access rights.  Personal work is saved in private spaces on hard disks that are password protected.

Communication:  Data files, programs and peripherals devices can be shared  Communication is improved via e- mail/chat/bulletin boards

Management:  Centralised back-up of files  Stations can be managed remotely

World Wide Web (WWW) To access the information on the www you need a browser application, AOL, BT and Internet Explorer are browsers. The www is made up of web pages which usually contain text, images and sound.

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

Search Engines Websites such as Yahoo and Google include a search engine that regularly runs programs called web crawlers to gather information about what pages are on the internet When you enter a search you are searching a database for words that match your entry.

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

Mailing Lists When your contacts increases you may sometimes want to send the same message to several people. This can be done by creating a MAILING LIST, you may want to have a list for friends, and another for family

Legislation The law has struggled to keep up with the rapid pace of change that the internet has brought to society and consequently new legislation has had to be introduced. The following are three of the most common laws concerning the use of electronic information and access to networks

Legistlation  Computer Misuse Act  Copyright Designs and Patents Act  Data Protection Act.

Computer Misuse Act This act was introduced to secure computer material against unauthorised access or modification. The three categories established are:  Unauthorised access (HACKING) including illicit copying of software.  The circulation of ‘infected’ material (viruses)  Intentional destruction of software or data.

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

Data Protection Act If someone holds data electronically about an individuals, then that individual has the following rights  To view a copy of the data being held on them  To have any inaccurate data corrected  To prevent receiving junk mail

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