Unit 2 - Chapter 4 (Transfer of Data) Flashcards
What is a computer network?
linking two or more computing devices together for the purpose of sharing data, software and peripherals & communication
What is LAN?
Local Area Network - Network over a small geographical area
What is WAN?
Wide Area Network - Network over a large geographical area
What is MAN?
Metropolitan Area Network - covers an area like a town or city
Advantages of networks
> Sharing devices such as printers saves money.
Site (software) licences are likely to be cheaper than buying several standalone licences.
Files can easily be shared between users.
Network users can communicate by email and instant messenger.
Security is good - users cannot see other users’ files unlike on stand-alone machines.
Data is easy to backup as all the data is stored on the server.
Disadvantages of networks
> Purchasing the network cabling and file servers can be expensive.
Managing a large network is complicated, requires training and a network manager usually needs to be employed.
If the file server breaks down the files on the file server become inaccessible. The computers can still be used but are isolated.
Viruses can spread to other computers throughout a computer network.
There is a danger of hacking. Security procedures are needed to prevent such abuse, eg a firewall.
Intranets
> Can only be accessed by certain people in certain locations - an internal network.
For example, the school intranet can only be viewed by staff, students and parents
Often, intranets used by companies can only be accessed while at work
Used for: sharing / publishing information and files communication (internal email, IM)
The information being shared may be sensitive or confidential e.g. company accounts
Extranets
> part of an organisations network that can be made available to outside users, for example customers or suppliers
gives limited access to resources and information
security of an extranet needs careful consideration so access is correctly restricted to certain areas of the network
Network topology
The conceptual layout of a network
Most common topologies
Bus
Star
Ring
Wired connections
Wired connections use cables to connect computers to the network. The most common type of connection is a Cat-5, also known as twisted pair. It is known as twisted pair as it contains 4 pairs of wires all twisted together in pairs. (see the bottom right image) Twisting the wires reduces electric interference and increases reliability.
NIC
A network interface card (NIC) is used to connect a computer to a network using a cat-5 cable. The interface card may be built into the motherboard.
Hub
A hub is a device which allows several computers to be connected together. The number of computers it can support is based on the number of connections, or ports, it has. A 8 port hub can support 8 computers. 16 port hub can support 16 and so on.
World Wide Web
The world wide web is an area of the internet that is used for storing a range of multimedia resources. It is the main area for websites.
Uniform Resource Locator
URL - A method for identifying the location of resources on the Internet
