CIE AS level Computer Science - Networks

WAN

Wide Area Network (network covering a very large geographical area)

LAN

Local Area Network (network covering a small area such as a building)

MAN

Metropolitan Area Network (network covering several buildings in a single city, i.e. a university campus) its smaller than a WAN but bigger than a LAN

PAN

A network centred around a person or their workspace

File Server

A server on a network where central files and other data are stored. They can be accused to a user logged unto the network

Hub

Hardware used to connect together a number of devices to form a LAN that directs incoming data packets to all devices on the network (LAN)

Switch

Hardware used to connect together a number of devices to form a LAN that directs incoming data packets to a specific destination address only

Router

Device enabling data packets to be routed between different networks (for example, can join LANs to form a WAN)

Modem

Modulator demodulator. A device that converts digital data to analogue data and vice versa so it can be processed by a computer

WLAN

A wireless LAN

WAP

Wireless Access Point which allows a device to access a LAN without a wired connection

Client-server

A network that uses separate dedicated servers and specific client workstations. All client computers are connected to the dedicated servers

Spread Spectrum Technology

Wideband radio frequency with a range of 30 to 50 metres

Node

A device connected to a network (it can be a computer, storage device or peripheral device)

Peer-to-Peer

Network in which each node can share its files with all other nodes. Each node has its own data and there is no central server

Thin Client

A device that needs access to the internet for it to work and depends on a more powerful computer for processing

Thick Client

A device which can work both off line and on line and is able to do some processing even if not connected to a network/internet

Bus Network Topology

Network using a single central cable in which all devices are connected to this cable so data can only travel in one direction and only one device is allowed to transmit at a time

Star Network Topology

A network using a central hub/ switch with all devices connected to this central hub/switch so all data packets are directed through this central hub/switch

Mesh Network Topology

Interlinked computers/ devices, which use routing logic so data packets are sent from sending stations to receiving stations only by the shortest route.

Hybrid Network

A network made up of a combination of other network topologies

Cloud Storage

A method of data storage where data is stored on off-site servers

Data Redundancy

A situation in which the same data is stored on several servers in case of maintenance or repair

Wi-Fi

Wireless connectivity that uses radio waves, microwaves. Implements IEEE 802.11 protocols

Bluetooth

Wireless connectivity that uses radio waves in the 2.45 GHz frequency band

Spread Spectrum Frequency Hopping

A method of transmitting radio signals in which a device picks one of 79 channels at random. If the chosen channel is already in use, it randomly chooses another channel. It has a range up to 100 metres

WPAN

Wireless Personal Area Network. A local wireless network connecting together devices in very close proximity (a house), i.e laptop, smartphone, printer etc

Twisted Pair Cable

Type of cable in which two wires of a single circuitry twisted together. Several twisted pairs make up a single cable

Coaxial Cable

Cable made up of central copper core, insulation, copper mesh and outer insulation

Fibre Optic Cable

Cable made up of glass fibre wires which use pulses of light rather than electricity to transmit data

Gateway

A device that connects LANs which use different protocols

Repeater

Device used to boost a signal open both wired and wireless devices

Repeating Hubs

Network devices which are a hybrid of hub and repeater unit

Bridge

A device that connects LANs which use the same protocols

Softmodem

Abbreviation for software modem; a software-based modem that uses minimal hardware

NIC

Network interface card - allow devices to connect to a network/internet

WNIC

Wireless network interface card/controllers

Ethernet

Protocol IEEE 802.3 used by many wired LANs

Conflict

A situation where two devices have the same IP address

Broadcast

Communication where pieces of data are sent from sender to receiver

Collision

A situation where two messages/data from different sources are trying to transmit along the same data channel

CSMA/CD

Carrier sense multiple access with collision detection - a method used to detect collisions and resolve the issue

Bit Streaming

A contiguous sequence of digital bits sent over a network/internet

Buffering

A store which holds data temporarily

Bit rate

The number of bits per second that can be transmitted over a network

On Demand (bit streaming)

A system that allows users to stream video or music files from a central server as and when required without having to save the files on their own computer

Real-time (bit streaming)

A system which an event in captured by camera and microphone connected to a computer and sent to a server where the data is encoded. The user can access the data as it happens live