NETWORKS

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NETWORKS OTHER ISSUES
What is a Network?

• A number of computers or terminals connected
  together make up a NETWORK.
• Can either be a WAN (Wide area network) or a LAN
  (Local area network)
• WANs may use many types of media eg. telephone
  lines, cables and radio waves

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TYPICAL TOPOLOGIES

• Star
• one or more smaller computers connected to a
  central host (mini or mainframe) eg. banks.

• Ring (Token ring)
• Used in LAN's
• electronic (data) token sent from workstation to
  workstation
• incoming data read from token.
• outgoing data attached to empty token.

• Communication is usually one-way around the ring
  no collisions
• One node going down disables the network.

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TYPICAL TOPOLOGIES (CONTD)

• Bus
• All nodes are connected to a single line via an
  interface box.

In buses and rings all nodes receive every
signal. Each node determines if the message is
addressed to that node either receiving the
message or passing it on.
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LOCAL AREA NETWORK (LAN)

• Consists of
• hardware - PC additional communications board
  in the computer
• a software package eg Windows XP
• cabling joining the computers and other
  peripheral devices together

• LAN
• Allows sharing of software, hardware (server,
  printers, modems) and information.
• Server workstation has large hard disk with
  application programs data others can access.

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CONNECTING NETWORKS
A hub is a central point that connects several
devices in a network together
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CONNECTING NETWORKS
Bridge combination of hardware/software to
connect similar networks eg.
Gateway hardware/software to connect different
networks eg. Routers Connect several networks
together and transmits data to its correct
destination.
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NETWORK ARCHITECTURE
The design of computers, devices and media in a
network .
Client-Server One of more computers act as a
server
Peer-to-Peer A simple inexpensive network that
typically connects less than 10 computers..
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NETWORK ARCHITECTURE (CONTD)
Internet Peer-to-Peer Called P2P, is an Internet
network on which users connect directly to each
others hard disk and exchange files over the
Internet eg. KaZaA which allows users to swap MP3
files via the Internet.
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WIDE AREA NETWORK (WAN)

• Wide Area Network (WAN)
• Network that covers a large geographic area (such
  as a city, country or the world)

10
Wireless Network
Used when it is inconvenient, impractical, or
impossible to use cable
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OTHER ISSUES
1. Employment The explosion in computer usage has
produced employment opportunities in the Computer
Industry maintenance, sales, manufacture
etc. General job shift less low skill jobs,
(which are often even less skilled, eg.
check-out) new jobs created are high skill

• 2. Crime
• The computer has made the committing of crimes
  more efficient.
• Computer Security Risks include
• System Failure
• Information Theft
• Software Theft
• Hardware Theft
• Computer Viruses, worms trojan horses
• Unauthorised access and use

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OTHER ISSUES (CONTD)
Virus potentially damaging computer program
that infects a computer and may damage files and
system software.
Worm copies itself repeatedly using up
resources and possibly shutting down the computer
or network
Trojan Horse is a malicious program that looks
like a legitimate program but when executed, can
erase files and damage hard disks.
How a Virus can spread through an e-mail message
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OTHER ISSUES (CONTD)
3. Security A computer system owner may choose to
build a number of controls and safeguards into
their system to protect the system and its data
against accidental or deliberate damage. Access
requirements physical - ID card software -
password voice recognition
finger print reader laser eye
scan Copy protecting software. Auditor checks of
the system.
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OTHER ISSUES (CONTD)

• 4. Privacy
• In our modern society, vast amounts of data is
  required about individuals to manage the
  community at a broad level. Eg. Collection of
  taxes.
• Computers provide a way in which large amounts of
  data can be stored cheaply but the security of
  such data is not ensured.
• Issues
• Information about yourself is stored on many
  computers.
• Paperwork for loans, bank accounts, magazine
  subscriptions, insurance claims, Medicare,ATO,
  Centrelink.