Computing 5 - Fundamentals of Computer Networks

Computer Network

A collection of computers linked together to facilitate communication and the sharing of resources and hardware, either wired or wirelessly, e.g. the internet.

LAN

Local Area Network - a network that covers a relatively small geographical location and is often owned and controlled/managed by a single person or organisation.

WAN

Wide Area Network - a network that covers a large geographical area and is usually owned and/or controlled by a group of organisations. They usually consist of several LANs connected together and are likely to be wireless or use fibre optic cables. The biggest example is the internet.

PAN

Personal Area Network - a network with a very small area, e.g. a room, that is centred around an individual. Bluetooth is a PAN and allow individual devices to connect to other pieces of hardware within a 10m radius.

Star Topology

A topology with one central node that has each computer or network device attached to the it. All data first goes into the central node and then is sent out to its destination; this means it is secure.

Bus Topology

A network layout in which there is one main trunk, or backbone, that all the various computers and network devices are connected to. Data broadcasted from one computer goes to all the other devices too and this means that it is less secure.

Router

A device that routes data packets across a WAN and acts as a node in a network, as packets are passed from router to router. It has an IP address.

Switch

A device that knows the MAC address of each individual device connected to it locally. It sends packets only to the intended recipient, using these.

NIC

Network Interface Card - required to connect any device to a network, and can either operate wirelessly or have a wired connection using a standard Ethernet cable.

IP Address

A number that uniquely identifies each computer or device connected to the Internet, that can change, depending on the location of the device.

MAC Address

A Media Access Control address is a hardware address that uniquely identifies each device on a network, and is permanent.

Fibre Optic Cable

A high performance cable that uses light to carry data, is fast, doesn't change with distance, and has little or no interference. Unfortunately, it is very expensive.

Twisted-Pair Copper Cable

A cable consisting of pairs of twisted wires covered with an insulating layer, that is cheaper than fibre optic, but has more interference, is slower, and its voltage decreases with distance.

Authentication

Identifying whether a user is authorised or not. Different methods include: a password, biometrics, and email confirmation.

Encryption

Makes data unreadable