Networks

Networks

1. Overview

   • Network card interface (NIC) is inside every computer
   • networks let computers share resources
   • Some connected by wires or by telephone lines
   • file server = shares programs and data files on backing storage
     • Print server = share a printer
       • database server = stores larger database
         • mail server = manages email traffic

2. Advantages

   • Hardwarecan be shared (less cost)
   • Software can be shared
   • Data cab be shared
   • Computers can communicate
   • Controlled by network manager
   • Easier to make scheduled back ups

3. Disadvantages

   • Cables cost
     • Networks can be attacked by hackers
       • Files can be compramised
         • Network crash caused havoc hard/soft ware and data cannot be shared

4. Types of network

   • Peer-to-peer = all computer are equal
     • Client-server = one high powered computer is the server
       • LAN = Local area network (in one area)
         • WAN = Wide area network (international)

5. Topologies

   • Bus = next to each other, one computer crash doesn't matter, slow
     • Star = connected to central HUB, 1 crash doesn't matter but is HUB crashes all are down
       • Ring = data is sent in a loop, one crash stops flow so all crash

6. intranet is the internet but in one organisation (restricted)

   • extranet is part of the intranet that can be accessed by authorised members

7. Network security

   • Passwords
   • Access rights to certain members
   • Encryption
   • Back ups
   • Firewall
   • Virus protection

8. Data transmission

   • Cable = metal copper or fibre optic
   • Wireless (microwave, infrared, radio)
   • Satellite
   • Bluetooth = connects to PDAs eliminated the need for cables
   • Packet switching = packs of data stored in binary code
   • Components
     • Switch = filters data packets and forwards them between network segements
     • Gateway = allows a LAN to connect to a WAN
     • Router = forwards data packets along a network. normally at gateways and configure with other routers to find the best route
     • Bridge = connects LAN to another LAN