GCSE Computing - Communication and Network

GCSE Computing - Communication and Network

1. LAN

   • Local - Area Network
   • It covers a small area
     • Such as one site or a building
       • E.g. School

2. WAN

   • Wide - Area Network
   • Covers a large geographical area
   • Most WANs are made from several LANs connected together

3. Parts of Networks

   • Router
     • Sends data packets on their way in the best direction
   • Switch
     • Reduces Network Traffic and increases speed
     • Smart, multi-plug adaptor only sends packets to the intendent recipent, using its MAC address
   • Hub
     • Central, multi-plug adaptor for computers and printers in a network
     • When a packet of data is received, it broadcasts the packet to all devices on the network
   • Modem
     • An electronic device that makes possible transmission of dta to or from a computer via telephone or other communicaton device

4. Client-Server

   • A central server supports a number of networked stations
   • People can just log into it and use it
   • Servers include files,prints, emails and webs
   • Waits for the request from the client then it uses the fecth,decode,execute procedure
   • Powerful Network
   • Advantages
     • Data can be backed up
     • Security is better
       • Data is held in one location
     • users can log in from any computer in the network
   • Disadvantages
     • Expensive to purchase
     • If any part fails, disruptions can occur
     • A specialist network and manager needed

5. Peer-to-peer

   • Sometimes referred to as P2P
   • An alternative to client - server network
   • No central server
     • Each computer holds its own data and applications
   • All computers have an equal status
   • Advantages
     • Easier to set up
       • Can be connected by a cable
     • No special software needed
     • Individuals can share a printer, router, modem, files and other hardwares
   • Disadvantages
     • Viruses are asly transferred
     • Data recovery and back-ups are not done centrally
     • Each computer has to have ts own back-up
     • Files are not centrally organised

6. Network topologies

   • Star network
     • Advantages
       • Fast data transfer
         • No data collision
       • If one cable faiils the other workstations are not affected
     • Disadvantages
       • Expensive to install
         • Lots of cable required as well as the switch
       • If the central device fails, the whole network is down
   • Ring Network
     • Advantages
       • Data is transferred quickly
         • Flow in one direction and no collision
       • More workstations can be added without degrading performance
       • Not affected by heavy traffic
     • Disadvantages
       • If one cable fails, the whole network fails
       • Privacy/security problems
         • Workstations may see data that is not for them
       • Any problems are hard to identify
   • Bus Network
     • Advantages
       • Easy to install
       • Cheap to install
       • Doesn't require much cable
     • Disadvantages
       • Main cable fails, whole network is down
       • More networkstations = slower network
         • Data collisions
       • Security risks
         • Every workstations on the network sees all the data

7. Definitions that are good to know

   • IP
     • Internet Protocol
       • An IP address is an identifier for a computer or device on a TCP/IP network
   • ISP
     • Internet Service Provider
       • It refers to a company that provided Internet services
   • AP
     • wireless Acces Point
       • Allows wireless devices to connect to it
         • It connects to a router
   • CSMA/CD
     • Carrier Sense Multiple Access/ Collision Detection
       • Set of rules determining how network devices respond when two devices colide (data collision)
       • Standard Ethernet networks use CSMA/CD to physically monitor the traffic on the line at participating stations
   • DNS
     • Domain Name System
       • An internet service that translates domain names into IP addresses
   • MAC
     • Media Access Control
       • The MAC address is a hexadecimal number that is unique to that particular device
   • HTML
     • HyperText Markup Language
       • It provides a standard format which any computer with web browser can interpret and display the pages
   • URL
     • Uniform Resource Locator
       • It is the global address of documents and other resources on the WWW (World Wide Web)

8. Network Protocols

   • TCP/IP
     • Transmission Control Protocol and Internet Protocol
     • It is used to exchange data between computers on computers on a network and route packets between networks
   • FTP
     • File Transfer Protocol
     • Used to transfer files between computers over a network
   • HTTP
     • HyperText Transfer Protocol
     • Used on WWW to transfer webpages and web content from the website host server to the computer requestiing the page
   • SMTP
     • Simple Mail Transport Protocol
     • Used to transport emails

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