1.3. Networks

• What does 'client' mean in computing terms?


  A device that makes requests to a server for data and connections.
• Explain a client-server network:


  • A client makes requests to the server for data and connections
  • A server controls access and security to one shared file store
• What does the acronym DNS stand for and what does it do?


  • Domain name system
  • It is made up of multiple domain name servers - it maps a domain name in a URL to an IP address
• What does 'hosting' mean in computing terms?


  Websites stored on dedicated servers.
• Explain what LAN stands for and what it does:


  • Local area network
  • It covers a small geographic area and the organisation using it owns all hardware for it
• Explain what a mesh network topology is:


  A topology where nodes are connected so there is more than one route to the desetination.
• What is network?


  Two or more computers or electronic devices that are connected with the purpose of communication.
• What is NIC?


  • Network interface card
  • Connects a computer to a computer network
• Advantages of using networks:

  • File sharing
  • Hardware sharing
  • Communication
  • Roaming access
• Advantages of using networks in a large networks:

  • Centralised maintenance and updates
  • Centralised security
  • User monitoring
  • Levels of access
• Disadvantages of networks:

  • Cost
  • Management
  • Spread of malware
  • Hacking
• What are the two kinds of networks?

  • LAN: Local Area Network
  • WAN: Wide Area Network
• Properties of WAN:


  • Over a wide geographic area
  • Not all infrastructure may be owned by the organisation
• What are the factors affecting network performance?


  • The number of devices on the network
  • The bandwidth of the transmission medium
  • The type of network traffic
  • Network latency
  • The number of transmission errors
• Each transmission medium has a different bandwidth:

  • Twisted copper wire: Up to 10 Gigabytes per second
  • Fibre-optic cable: Up to 100 Gigabytes per second
  • Wi-Fi(home networks): Up to 600 Megabytes per second
  • Business Wi-Fi: Up to 6 Gigabytes per second
• The bandwidth of the medium is shared between each connected device - each new device that joins, the bandwidth would be split between all the devices
• What are some examples of how different types of network traffics may affect bandwidth distribution?


  Streaming a high definition video requires more bandwidth than streaming a low definition video.
• Latency

  • Measure of how long it takes a message to travel from one device to another across a network
  • A switch based network will usually have a lower latency compared to a hub based network
• Transmission errors are collisions of signals, leading to transmission fail - this is caused by great numbers of devices on a network.
• What are two most common network models?

  Client-server networks and peer-to-peer networks.
• Peer-to-Peer Networks:

  • All computers have equal status
  • No server or clients - just peers
  • Peer computers store their own files, which can be accessed by other peers
  • Normally used by smaller organisations with little computers
• A client-server networks consists of a client and a server.
• What is the computer that manages and stores files in a client-server network called?


  A server.
• Typical servers:

  • File servers
  • Application servers
  • Web servers
  • Print servers
  • Mailing servers
• Clients usually rely on servers and do not store data.
• Client-server networking is usually used by large organisations.
• What hardware are needed to connect a computer or device to a network?

  • A network interface controller
  • A transmission medium
  • A connection point
• A connection point can be a router, hub, switch or a wireless access point.
• Network interface controllers provide a method of connecting to a network.
• Unlike PCs, mobile devices such as tablets, smartphones and many embedded devices only feature a wireless NIC, giving only wireless connection, which provides a radio transceiver.
• Transmission media carry data signals from one computer to another and can be wired or wireless.
• Properties of twisted copper wire:

  • Cheap cost
  • Maximum transmission speed of 1 gigabit per second
  • Maximum reliable distance of 100 metres
• Properties of fibre-optic cables:

  • Expensive cost
  • Maximum transmission speed of over 40 terabits per second
  • Maximum reliable distance of over 2 kilometres
• Wired connections are reliable and not usually subject to interference, however are usually required to stay in place due to the limited mobility.
• Hubs are small devices that allow wired devices to connect to a network.


  They have no knowledge of the devices connected; any arrived traffic is transmitted to all connected computers.
• What is one disadvantage of a hub?


  Its network performance is easily affected as it sends unnecessary transmissions.
• What is the difference between switches and hubs?


  Switches record computers and their connected ports therefore forwards traffic to its intended recipient only.
• What is a WAP?


  A connection point that creates its own wireless network - it sends wireless traffic onto the main wired network.
• How does WAP allow wireless connections to the network?


  It uses a radio transceiver to make wireless connections.
• Routers:

  • One of the most commonly used connection devices
  • Used to send data signals across the internet