Networks

• what is network?


  a system that allows computer systems to communicate + share resources with each other
• what is a LAN?

  • Local area network

  • computers connected over a small geographical area

  • uses dedicated hardware
• what is a WAN?

  • Wide area network

  • computers are connected over a large geographical area

  • uses other infrastructure
• what is a packet?


  small digital 'envelope' which sends requests and information around the world between computers
• what is a WAP?

  • wireless access point

  • allows for wireless devices to connect to a network, including Wi-Fi and Bluetooth
• what is a router?

  • an interconnection device used on networks to connect 2+ devices
• what is a switch?

  an interconnection device which helps to avoid data collisions by creating a direct connection to each device on a network. in a LAN, it connects a group of devices together
• what is a NIC?

  • Network interface card

  • Allows a computer to connect to a wired network

  • contains a MAC address (physical hardware address)
• examples of transmission media

  • ethernet

  • fibre optic

  • coaxial cable
• how do packet collisions affect the performance of a network?

  when data collisions occur, both packets need to be resent, making it seem like the network is slow. this can be fixed with a switch.
• how does transmission media affect network performance?

  different transmission media have different bandwidths (data transferred ÷ unit of time) and latency (time for 1 packet to arrive), which affect the performance
• what is a client in a network?

  a device which requests and receives data from a server
• what is a server in a network?

  a computer which receives and responds to requests from a client
• what is a peer in a network?

  someone/something of the same status/ability
• what is a client-server network?

  • relies on a central server

  • clients request services from the server

  • requires additional hardware
• what is a peer-to-peer network?

  • all computers have equal status

  • each device can act as a client/server

  • all devices request and provide resources
• how are files managed in a client-server network?

  all files are stored centrally, meaning clients can access files from any computer
• how are files stored in a peer-to-peer network?

  peers store their own files, which can be accessed by other peers on the network
• how are backups managed on client-server networks?

  • backups are easy to make

  • all data backed up in 1 go

  • individual computers are not backed up
• how are backups managed on peer-to-peer networks?

  all peers are responsible for backing up their own data
• how does security differ from different types of networks?

  • client-server = security measures managed centrally

  • peer-to-peer - peers are responsible for security measures
• when are different networks used?

  • small networks = peer-to-peer

  • client-server is useful for lots of computers and a high traffic environment
• what is a DNS?

  • domain name server/system

  • has a list of domain names, their URLs, and the matching IP addresses to send packets to
• what is hosting?

  a computer holding your website
• what are web servers?

  they hold the data of the website, and receive requests from clients who want to access the website
• what is the cloud?

  • network of servers that store data or run apps

  • accessed over the internet
• advantages of the cloud

  • global access

  • sync across multiple devices

  • remote backups + security

  • easy to upgrade
• disadvantages of the cloud

  • no internet = no access

  • not always free

  • vulnerable to hacking

  • depend on host for security and backups
• what is a star topology?

  all devices are connected to a central device e.g. switch, router, therefore every message has to go through the central device
• what is a mesh topology?

  devices are connected to lots of other devices, with no central switch
• what is a partial mesh topology?

  most devices are connected to several other devices
• what is a full mesh topology?

  all devices are directly connected together
• adv of a star topology

  • fewer cables

  • easy to add/remove devices

  • simple
• disadvantages of a star topology

  • if the central switch fails, the whole network fails

  • causes a bottleneck in a busy network
• adv of a mesh topology

  • allows packets to be routed around bottlenecks

  • more reliable - a single failure won't break the whole network
• cons of a mesh topology

  • needs more cables

  • hard to add/remove devices

  • hard to troubleshoot
• what are Wi-Fi connections and how do they work?

  • radio waves transmit data at 5GHz or 2.4GHz

  • most common in LAN

  • devices communicate with a WAP - standalone router/switch
• what is Bluetooth?

  • another type of wireless connection

  • shorter range than Wi-Fi

  • used for a direct connection between 2 devices

  • file transfer is possible but slow
• pros of ethernet


  • more secure

  • more stable
• cons of ethernet

  requires physical cables, which can be expensive and cause trip hazards