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Local & Wide Area Networks Networks • A network is two or more computers linked together • Networks are used to share programs, data and resources. • There are two main types of network • LAN (Local Area Network) • WAN (Wide Area Network) • Computers on a network are called stations. • One station on the network is a powerful computer called a file server. Local Area Network (LAN) • covers a small area such as a room, building and is usually owned by an individual, company or small organisation • Is a fast network • Is connected by its own wiring Advantages of LAN’s • Share data and programs between stations • Share resources, e.g. peripherals such as printers, scanners. • Sharing makes it cheaper • Use e-mail service Advantages of LAN’s • Keep data secure using passwords • Reduce unauthorised access using different level of access (read-only) • Allow users to access their files from any computer on the network • Allow users to work on the same files at the same time (multi access) LAN Transmission Media • • • • • copper wire fibre optic (glass) infrared bluetooth WiFi WAN (Wide Area Networks) A network that covers a large geographical area such as a country or the whole world!! The Internet is one example Advantages of WAN’s • Same as LAN’s except you do not usually share peripherals • Send e-mail worldwide • Video conferencing • Voice over data (Free phone calls worldwide) WAN Transmission Media Any communication carried over a long distance is called telecommunication. A WAN uses the telephone system which includes: • • • • Copper cables Microwave transmission links Satellite links Optical fibres links Network Security Data can be lost through • accidents • system failures • deliberate action (unauthorised access) There are two ways of securing data: • physical security • electronic security Physical Security • locks on rooms • identity cards (Magnetic stripe or Smart card) • biometrics - fingerprint, iris scan or voice print • stand-alone computer Electronic Security • Passwords • Levels of access • Encryption (putting into code) • Very important in wireless networks Absolute Security "Three may keep a secret if two of them are dead" Ben Franklin NO NETWORK!! Client & Server Network Server • A computer that delivers data and software to other computers (clients) linked by a network. • Usually has • Fast processor • Large memory • Large hard disc Types of servers • • • • File Mail CD Internet File Server A file server stores • programs • data • list of all users allowed access to the network (authorised users) • Once you have logged-on the file server allows you access to the network (on-line) • Logging–on: identifies a user to the file server ( usually by entering username & password) Network Interface Card (NIC) • This is a small circuit board that allows the computer to communicate with a computer network. • Some computers have a wireless network interface card that allows them to communicate with a nearby LAN Social, Legal & Ethical Issues Social Issues Teleworking This is the process of • • • • working from home and using a computer to connect to a wide area network to communicate with the office. There are several advantages to employees and employers: Advantages of Teleworking Advantages to employees: • Choose own working hours • Save money on fuel, child care costs • Reduce congestion on the roads, pollution and travelling time Advantages to employers: • Do not have to provide premises, heating lighting, rent, rates. Disadvantages of Teleworking Disadvantages to Employees: • May not be given same rights to health & safety (electrical faults) • Workers may become isolated or lonely Disadvantages to Employers • Must ensure all electrical equipment complies with health & safety issues • Must take responsibility for ‘information security’ of remote workers Social Benefits of WAN Advantages: • Improve communication in isolated areas & reduce isolation • Allow people to keep in contact with family abroad via e-mail & websites • People connected to the Internet have access to a large pool of information (Information rich) Disadvantages: • May increase social isolation as more people go on-line (become detached from real world) • Costly – those not connected may be further disadvantages (Information poor) Legal Issues Legal Issues Laws which affect computers include: • Computer Misuse Act • The Data Protection Act • The Copyright, Designs & Patents Act • The Privacy and Electronic Communications Regulations 2003 Computer Misuse Act • Unauthorised access (hacking) • Creating a virus • A progam • that copies itself • that may cause harm The Data Protection Act (1998) This Act compels any company to take specific measures to ensure that all personal information held about living (identified or identifiable) individuals is processed according to eight Data Protection Principles Data Protection Act Principles Data users must • Obtain and process the data fairly and lawfully • Register the purpose for which they hold it • Use only for this purpose • Hold only adequate and relevant data • Keep data accurate and up-to-date • Not keep data longer than necessary • Give individuals access to their own data • Take appropriate security measures Data Protection Act Exemptions • • • • • Law Enforcement National Security Examination Marks and Examiners’ Comments Adoption Records and Reports Lawyer-client communications. The Copyright, Designs and Patents Act (1988) • “intellectual property” • “expression of an idea” • all computer software, whether covered by a specific licence or not, is copyrighted under this Act. • the program itself • screen shots • associated documentation Privacy and Electronic Communications Regulations 2003 • This act makes it illegal for companies to send you unsolicited e-mail (Junk Mail). Note: Unsolicited means something that you did not ask for. • Companies must get permission from an individual before they can send them an e-mail or text • An Individual must be given the choice of refusal Ethical Issues Ethical Issues These are concerned with people’s judgement as to what is right or wrong. Invasion of personal privacy • Is it acceptable for government bodies [NSA(US), GCHQ(UK)] to intercept private data sent across networks to prevent terrorism & crime Censorship & freedom of speech • Should anyone be able to set up a website even though it is used to incite hatred & racism • Should the government be able to block these web sites, e.g. bomb making Local & Wide Area Networks End of presentation