7. Networks GapFill

A network is an interconnected system of multiple computers and related devices to facilitate communication and sharing of resources. In order to connect a computer to a network, that computer requires a   clientnetwork interface cardservernode, which is a printed circuit board containing an Ethernet  socketconnectorportgateway, a wireless antenna or both. If this is a wired connection, the other end of that cable can be plugged into one of several other devices. It might simply be another computer. Alternatively, it could be a   routerswitchhubwireless access point, to which many Ethernet connections can be made, with incoming signals simply being broadcast across all other connections. Slightly more sophisticated is a  hubswitchrouterrepeater, which has similar behaviour initially, but is capable of learning which devices are connected to which ports, meaning broadcasting is not necessary.

For connection with more flexibility for movement, a  switchnetwork cardrouterwireless access point would need to be installed. This would be connected, via a cable, to the rest of the network, and there could be many of these within the same network, depending on the size of the building. Ultimately, the connection would need to go via a  gatewayrepeaterwireless access pointrouter if this network were to need access to the Internet.

Networks can be configured differently, depending on their need. In a  buspeer-to-peerclient-serverstar network, one computer provides a service, such as access to a printer, which other devices can request. Those other devices do not provide that service themselves. Conversely, a  starclient-serverpeer-to-peerbus network allows all devices to both provide and request services. A disadvantage of this approach is  the loss of a host bringing down the networkpotential overload of requestsa lack of centralised backupfailure to utilise all hosts' capabilities.

In order for devices on a network to communicate effectively, protocols are required. These include  UDPDHCPHTTPFTP, which is used in the communication of web pages, and  SMTPPOP3IMAPHTTPS , which allows emails on the same account to be viewed on multiple clients. These protocols feature in a conceptual model called the  IP stackTCP/UDP stackTCP stackTCP/IP stack, which has four layers. In descending order of abstraction, these are called  dataapplicationnetworktransport,  datapresentationtransportnetwork,  networkpresentationtransportsession and link. Each protocol operates at one of these layers.