Networks

Lewis Hunt
Mind Map by Lewis Hunt, updated more than 1 year ago
Lewis Hunt
Created by Lewis Hunt over 5 years ago
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Description

AS - Level Computing (Component 1) Mind Map on Networks, created by Lewis Hunt on 05/20/2016.

Resource summary

Networks
  1. An interconnected set of devices
    1. Each device is called a node
      1. Most computing devices are connected to many networks via the internet
      2. Private networks
        1. Advantages:
          1. The institution controls security
            1. Security issues typically involve who is allowed what privileges
              1. Software is totally under the institution's control
                1. The institution is not reliant on someone else providing reliablility
                2. Disadvantages:
                  1. They need specialised staff
                    1. A need to make own arrangements about security and backups
                    2. Precautions that can be taken against loss of data of functionality include:
                      1. Redundancy - duplicate servers and other equpiment
                        1. Backup regime
                          1. Failover systems - automatic transfer to backup system in the event of a failure
                            1. Disaster recovery plan - processes, procedures and personnel responsibilities in the event of a major incident
                          2. Hardware:
                            1. Network Interface Card/Controller
                              1. Receives and sends electrical signals.
                              2. Router
                                1. Device to connect networks
                                  1. Receives and forwards data packets
                                    1. Directs packets to next device. Uses a table or an algorithm to decide the route
                                    2. MAC addresses
                                      1. 48-bit identifier
                                        1. Permanently added to a device by the manufacturer
                                          1. Human readable groups of 6 bytes (octets)
                                            1. 08:01:27:0E:25:B8
                                          2. Switches
                                            1. Devices to connect other devices on networks
                                              1. Use of packet switching to send data to specific destinations making use of hardware addresses
                                                1. Operate at level 2 or 3 of the OSI model
                                                2. Hubs
                                                  1. Connect nodes together by broadcasting a signal to all possible destionations
                                                    1. The correct destination will accept the signal
                                                    2. Wireless Access Point
                                                      1. Devices can use wireless to connect to a WiFi network
                                                        1. Can cannot from distances of up to about 100 metres
                                                        2. Transmission Media
                                                          1. Networks use cables to connect the nodes
                                                            1. Copper Conductors
                                                              1. Fairly cheap
                                                            2. Wireless is used for part of the network
                                                              1. Slower than cables and poses security threat
                                                            3. Security Issues
                                                              1. Eavesdropping by intercepting the wireless signals
                                                                1. Reduce risk by
                                                                  1. Hiding SSID (service set identification)
                                                                    1. Limits usefulness to new users
                                                                    2. Encrypition
                                                                      1. Most use WPA and WPA2 which use only-once encryption keys
                                                                      2. Limiting access
                                                                        1. Only allow access to known MAC addresses
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