A computer network is a number of computers linked together to allow them to share resources. Networked computers can share hardware, software and data. Most computer networks have at least one server. A server is a powerful computer that provides one or more services to a network and its users. For example, file storage and email.
LANs and WANs
There are two main types of network:
1.Local Area Network (LAN)
2.Wide Area Network (WAN)
A LAN covers a small area such as one site or building, eg a school or a college.
A WAN covers a large geographical area. Most WANs are made from several LANs connected together.
•The Internet is a WAN.
•A network of bank cash dispensers is a WAN.
•A school network is usually a LAN.
•LANs are often connected to WANs, for example a school network could be connected to the Internet. •WANs can be connected together using the Internet, leased lines or satellite links. Advantages and disadvantages of networks
•Sharing devices such as printers saves money.
•Site (software) licenses are likely to be cheaper than buying several standalone licenses. •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 file server. Disadvantages
•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. Email might still work if it is on a separate server. 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, particularly with wide area networks. Security procedures are needed to...