Computer networks & topologies

• What does WAN stand for?

  Wide Area Network
• Define a WAN.

  Any network in which the computers communicate using resources supplied by a ‘third party carrier’ such as BT.
• What resources does a WAN use?

  A WAN uses cables, telephone lines, satellites, or radio waves to connect two or more remote locations.
• Give an example of a WAN.

  The Internet is the largest WAN in the world.
• List organisations that may use WANs.

  Banks, governments, research organisations
• List devices that utilise the internet (ex. PCs)

  Mobile devices, Parking meters, Smart meters, Cars, Kitchen appliances, Animal trackers
• How are IPv4 addresses displayed?

  IPv4 addresses are four 8-bit (0-255) numbers separated by dots -- (e.g 72.129.214.16)
• How are IPv6 addresses displayed?

  Newer IPb6 addresses are 128-bit numbers represented in hex.
• What is Packet switching?

  Files are broken into packets (512 bytes) with a header containing the IP addresses to and from, the no. of packets in total, what no. the packet is in the sequence, and error checking data.
• What is the DNS?

  The Domain Name System (DNS) is made up of domain names (e.g Google.co.uk). A DNS server translates a web address into an IP address.
• What is a NIC?

  A Network Interface Card (NIC) is a computer hardware component that connects a computer to a computer network.
• What is a MAC address?

  A Media Access Control (MAC) address is assigned to each Network Interface Card (NIC) by the manufacturer.
• How is a MAC address used?

  As IP addresses change, routers use the MAC address (permanent, unique) of the next router to send data packets.
• What is a LAN?

  LAN Stands for Local Area Network ; a LAN operates on a single site.
• What is the difference between a LAN and a WAN?

  LANs are local and located within one location such as a building ; WANs connect networks at remote locations via leased lines.
• Name 3 advantages of networks.

  Computers can share resources such as printers.

  
  

  Files can be accessed through any computer in the network.

  
  

  Data is easy to back up as it is stored centrally on the server.
• Name 3 disadvantages of networks.

  Purchasing the network hardware is expensive,

  Managing a large network is complicated, Viruses may be able to infiltrate the network and infect every computer.
• Describe a Star network topology.

  The server connects to a switch or hub, which then connects to all the devices (PCs, printers) in the network.
• Name 2 advantages of a Star network topology.

  -**Fast data transfer to the hub** as each wire isn’t shared with other computers.

  -If one cable fails, the other computers are not affected.
• Name 2 disadvantages of a Star network topology.


  •If the central switch fails the whole network goes down.

  
  

  •Requires **additional hardware** such as the central switch and network cables.
• Describe a Mesh network.

  In a Full Mesh network, all computers are directly interconnected.

  
  

  In a Partial Mesh network, all computers are still interconnected however not all of them are directly connected and may travel through another computer.
• Explain how Mesh networking works.

  Nodes (computers) act as routers for data in order to relay data in the network.
• Name 3 advantages of a mesh network.

  No single point of failure.

  Expansion and modification can be done without disrupting the network.

  Data can be transmitted from different devices simultaneously.
• Name 3 disadvantages of a mesh network.

  Can involve redundant connections.

  Expensive to install cabling if using wired connections.

  Network administration and maintenance is difficult.
• Explain what a Router does.

  Routes packets of data towards their destination.
• Explain what a Switch does.

  **-Sends data to the appropriate node (connected computer.)**

  
  

  Switches connect each node (computer) in a network via the MAC address of all connected devices. When data packets arrive, they send it to the correct computers as opposed to Hubs, which send the data to all computers.
• What is Ethernet?

  -Local networking protocols **which describes how devices should format transmission-ready data between computers** on the **same network.**
• What is Transmission media?

  -The route that communication is sent through the network (i.e what type of wire)
• Name five types of transmission media.

  Ethernet cable

  Fibre optic cable

  Wi-Fi / Wirelessly

  Coaxial cable

  Copper cable
• What is Bluetooth?

  Bluetooth is a wireless method of connecting devices over a short distance via radio waves.
• What is a Wireless access point?

  A Wireless Access Point is the device responsible for allowing wireless devices to connect to a wired network through Wi-Fi.

  
  

  Home Wi-Fi routers usually combine the functions of the switch, router, and wireless access point in one box.
• Name the main advantage and disadvantage of using the 2.4GHz frequency.


  Advantage: Greater range and coverage

  Disadvantage : More interference as this frequency is more crowded.
• Name the main advantage and disadvantage of using the 5GHz frequency.


  Advantage: Less crowded space, higher data transmission rates.

  
  

  Disadvantage: Less able to penetrate through walls.
• Define Encryption.

  Encryption is the encoding of data so that it can no longer be easily understood.
• What is Symmetric encryption?

  A single key is used to encrypt and decrypt a message and must be given to the recipient of your message to decrypt the data.
• What is Asymmetric encryption?

  Two keys are used - one (public key) to encrypt and the other (private key) to decrypt data.

  This is more secure as it means you never have to send or reveal the decryption key.
• Name the two most common wireless security standards.

  WEP (Wired Equivalent Privacy - Old)

  WPA (Wi-Fi Protected Access - New)
• Explain the client-server model.

  The client sends a query to the web server, which then sends the search request to the database. The database then forwards the response through the web server back to the client.
• Name 3 advantages of the client-server model.


  Only one file server needs to be backed up and files can be accessed from any computer.

  Email servers provide a central place for email that is then accessed from different devices.

  One print server can manage all files to be printed, allowing one printer to be shared by many computers.
• Name the features of a peer-to-peer network.


  Suitable for small companies with few computers.

  No central server controls files or security.

  All computers can easily see files on all other computers.

  All computers can communicate with each other without going through a server.