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Created from P.M.T. and Ada Comp. Sci notes
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What is a network?
Two or more computers connected together with the ability to transmit data between each other
What are the advantages of a network?
The ability to share files
The ability to have multi-user systems
The ability to share expensive hardware devices between multiple users
The ability for the organisation to track what users are doing (this can of course be a disadvantage for the individual user)
What are the disadvantages of networks?
Extra hardware costs (cabling and connection devices)
Greater security risks
The cost of having to have employ someone to look after the network (depending on the size of the network)
What is a local area network?
A network which is spread over a small geographical area or a single site
LAN is the abreviation of…
…abreviation of local area network
What is a wide area network?
A network which that connects two or more networks over a large geographical area
WAN is the abreviation of…
…abreviation of wide area network
What is a protocol and why must they be standardised?
A set of rules defining how two computers communicate with each other
They are standard so that all devices have a designated method of communicating with each other, regardless of manufacture
What is a proxy?
A server that acts as an intermediary, collecting and sending data on behalf of the user
What are the benefits of using a proxy?
The privacy of the user is protected and they remain anonymous
Can be used by administrators to prevent access to sensitive or irrelevant information at work or at school
The proxy server can cache frequently used website data making it faster to load
What is a network interface card/contoller?
A hardware device that is used to connect a computer/device to a network
Each NIC has a unique MAC address
What is a wireless access point?
A hardware device that allows wireless devices to connect to a network
What is a modem?
A hardware device used to modulate the electrical signal, i.e. to change the signal so that it can be sent through a cable that uses a different technology.
What is a gateway?
A network device that provides a link between two dissimilar networks (e.g. a LAN and the internet)
What is a firewall?
A hardware device / piece of software that monitors and filters traffic going to and from a network.
Why are firewalls used?
To prevent unauthorised access to a network.
To restrict applications that are used internally that have internet access.
To restrict websites that can be accessed from within the network.
What is a bridge?
A network device that provides a link between local area networks
Purpose of a network switch
Joins computers/devices together on a LAN
Receives packets/data
Recipient’s MAC address is given in packet header
Send packets/data out the correct port to the specific computer device
What is a router?
A network device used to connect two or more networks together.
Describe a peer-to-peer network
A network in which computers are connected to each other so that they can share files.
Each device effectively acts as both a server and client, as it can both provide and request resources
What are the advantages of a peer-to-peer network?
Cheaper to set up
Easy to maintain
Not dependent on a central server
Specialist staff are not required
What are the disadvantages of a peer-to-peer network?
Impossible to trace the origin of files
Backups must be performed separately
Poorer security
May be difficult to locate resources
Describe the client-server network
A network that consists of terminals known as clients connected to a server.
The server is a powerful, central computer. The server holds all of the important information and resources.
The server has greater processing power than the terminals
The server provides access to a resource/service
Client computers connect to server
What are the advantages of client-server compared to peer-to-peer?
One location to backup
Centrally administered in one location - easier to manage users/access
Easier to keep data secure.
Technicians can more easily remotely install / monitor
What are the disadvantages of the client server model?
The server is a centrla point of failure
Can be expensive to set up - server hardware is costly
Can be expensive to maintain - requires specialist staff
Unshielded twisted pair cable
Consists of twisted pairs of copper wires
Resilient to interference - twisting means that any interference would affect both wires of the pair in the same way, which cancels out the interference
Reliable up to 100 metres distance
UTP is the abreviation of…
…abreviation of unsheilded twisted pair
Fibre-optic cables
Cables that carry light
Not affected by electical interference
Can carry signals over very long distances
Coaxial cables
Type of electrical cable that can be used to carry data
Has numerous issues with poor connections
Not commonly used anymore