10. Networks

• What is a network?

  When computers are joined with digital connections
• Signals travel through the transmission media
• Wired network

  Signals travel through metal wires or fibre-optic cables

  Wired connections offer more privacy
• Wireless network

  Wireless connections are needed if you want to use mobile devices

  Signals travel through the air e.g as radio waves
• LANs

  What are they?

  What type of connection?

  Give an example of one?

  Joins computers on the same site or building

  Uses cables or wireless owned and used by a single organisation

  E.g the network in an office or a school
• WANs

  What are they?

  What type of connection?

  Give an example of one?

  Joins computers on different sites,cities or countries

  Uses shared transmission media such as publicly owned cables

  E.g the network that connects the ATM in a village to a bank in a distant city
• What is a star network?

  Each computer is joined to a central device

  
• Pros and cons of a star network?

  Pros:

  -If a device or cable is disconnected , the rest of network is unaffected

  -Simple to add more devices to th enetwork

  -Better performance than other setups

  Cons:

  -Every device needs a cable to connect > can be expensive

  -If there's a problem with the switch server whole network is afected
• What is a mesh network?

  A network where each device connects directly to every other device. There is no central point

  
• Pros and cons of a mesh network?

  Pros: - Data transfer can be quick. This is due to having multiple connections. - Can cover large areas with multiple nodes - Resistant to single point of failure ; If you get a break in any of the connections you can stil route your traffic via another route Cons: - Lower overall speed compared to traditional networks - Higher initial setup cost ; Lot more cabling and switch hardware required which will add to cost for large networks - Limited scalability
• What is a client server network

  A group of devices connected to a central computer which manages the network / stores files centrally
• Pros and cons of a client server network?

  Easier to perform back-upsEasier to manage security fielsServers are very reliable , always onEasier to install software updates to all computersCons

  Server may overload if too many clients access it at onceServer is a single point of failure

  Requires IT specialist to maintain

  Can be expensive to set up
• What is a peer to peer network?


  A group of devices connected to share data with each other in which all devices are equal and connected without a server
• Pros and cons of a peer to peer network?

  Pros: Easy to maintainSpecialist staff not requiredCheaper to set upNo dependency on single computer

  Cons: Network is less secureUsers have to manage their own backupsDifficult to maintain a well ordered file storeMachines prone to slow down when other devices access them
• Give 4 types of server?

  -File server stores files for client computers

  -Email server sends and receives emails for the client computers

  -Printer server sends files to a printer

  -Web server provides content such as a web page through an internet connection
• Why is the internet a mesh network?

  It connects devices all over world. the devices can communicate because they all use the same communication protocols
• What four pieces of hardware are needed to make a network?

  Wireless Access Point (WAP)

  Switch

  Router

  NIC ( Network interface controller)
• Function of a WAP?

  Sends out signals such as radio waves to make a wireless connection
• Function of a switch?

  Connects several computers e.g in a star network.

  checks each message and sends it to correct computer
• Function of router?

  Connects one network to another e.g your school network to the internet
• Function of NIC?

  Electrical components inside a computer that let it send and receive network signals
• Give 5 factors affecting the performance of Networks?

  bandwidth ,number of users , transmission media , error rate , latency
• How does the number of users affect Network performance?

  if there are too many users / devices on the same network it can cause the network to slow down if there is an insufficient bandwidth for the data
• How does error rate affect Network performance?

  A less reliable connection increases number of errors that occur when data is transferred meaning data has to be resent until it arrives correctly.Length of cable is also a factor
• How does Transmission media affect Network performance?

  Wired connections have higher bandwidth than wireless connsFibre optic cables have higher bandwidth than copper cables due to less interference
• How does bandwidth affect the performance of networks?

  Higher bandwidth , greater the network performance
• How does latency affect the performance of a network?

  This is the delay from transmitting data to receiving it.This can be increased by not having the correct network hardware to direct traffic around the network appropriately, causing 'traffic jams' and therefore slowing data down
• What will happen if there isn't enough bandwidth or too many devices on the same network?

  The network will slow down due to insufficient bandwidth