Hub,Switch,Routers,Client,Nic

Different networks and protocol!

Hub

A Hub receives all data sent over the network and sends it to all the other devices on the network. Only the device who the data packet is for will acknowledge it, the other device will ignore it.
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Switch

A switch is a bit more intelligent than a Hub and it learns which devices are on the network and only sends the data packet to the computer who is the intended recipient.This is more efficient than a Hub as it doesn't result in lots of unnessesary network traffic.
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Router

A router is cleverer still than both Hubs and Switches.it can redirect network traffic and deal with different packets in different ways. it can protect the computers on the network by hiding them from the outside world. some routers have a modem built in and wireless capabilities.
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Client server network

In your school you will be able to use your files on computers in different buildings. this is because they are not stored on the computer that you are using but are on a file server somewhere else in school. the file server is a specialised computer with a different role to the normal pc. there will also be an email server and a web server on the network.

in a large network it is common to have shared files and resourses on centralised servers. the computers that you use around school are referred to as clients. the advantage of a client server network is that management is centralised and clients are not dependant on other clients just the server. in smaller offices this is not practicle if you run a small company with a handful of computers it is not cost effective to have a specialised server or someone to run the network.

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Peer to peer network

In a small office the computers will simply be cabled together. each computer is configured so it will share specified files and folders with other peer computers on the LAN,PCs on the LAN can only access files on another computer if access rights have been granted. this is called a peer-to-peer network because all of the computers have equal status and the same role in the network.
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A ring network

The ring network is a circle shaped network that only one computer can communicate at a time, also the data packets can only travel in a clockwise direction. So if the first computer desires to send something to the fifth then the fifth computer must wait for the data packet to pass the second,third and forth.The reason the ring network is not a popular style is because if the circle breaks the whole thing cannot run.
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A star network

The star network is a star shaped network that multiple computers can run and communicate at one time, that is why this method is common and used in schools.With this network the data packets can be passed in any direction and is more efficient than other networks.This network is good because even if a line breaks, it will not affect the other computers only that one.However if the server breaks down then everything stops working.
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A bus network

The bus network is a long line with smaller ones connecting computers to it.Computers at any time can be attached, however like the ring network only one computer can be communicating at a time, once one is being used you have to wait until the data packet has come to you for you to use.This, just like the ring network is not a very good method because if the line breaks none of the attached computers will be able to work.
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WAN

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Wide-Area-Network

Wide area network is multiple networks like the ring,star,bus networks all connected together to make one big working communicating network.An example of a wide area network is the internet.(One tesco store has a LAN, however many tesco stores around the country connected makes a WAN.)

LAN

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Local-Area-Network

A local area network (LAN) is a computer network that interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media. The defining characteristics of LANs, in contrast to wide area networks (WANs), include their usually higher data-transfer rates, smaller geographic area, and lack of a need for leased telecommunication lines.

NIC

In computer networking, a NIC provides the hardware interface between a computer and a network. A NIC technically is network adapter hardware in the form factor of an add-in card such as a PCI or PCMCIA card.

Some NIC cards work with wired connections while others are wireless. Most NICs support either wired Ethernet or WiFi wireless standards. Ethernet NICs plug into the system bus of the PC and include jacks for network cables, while WiFi NICs contain built-in transmitters / receivers (transceivers).

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SERVER

  1. A computer or computer program that manages access to a centralized resource or service in a network.
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CLIENT

A client is a piece of computer hardware or software that accesses a service made available by a server. The server is often (but not always) on another computer systems, in which case the client accesses the service by way of a network.

WHAT IS A NETWORK?

A network allows computers to communicate with each other and share resources. Eg. Storage, Internet access.

PROTOCOL

Protocols are a set of rules that define how computers and devices communicate. The Internet relies on a number of protocols in order to function properly. A protocol is simply a standard for enabling the connection, communication, and data transfer between two places on a network. Here are some of the key protocols that are used for transferring data across the Internet.
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Examples

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.

FTP stands for File Transfer Protocol. It is used to transfer files across the Internet. FTP is commonly used by web developers to publish updates to a website (i.e. to upload a new version of the website).

Where HTTP is used for displaying the file in your browser, FTP is used simply to transfer the file from one computer to a specified location on another computer. You can use FTP to transfer the files from your computer to a remote computer (such as a web server), or to transfer from the remote computer to your local computer.

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Gopher offers downloadable files with some content description to make it easier to find the file you need. The files are arranged on the remote computer in a hierarchical manner, much like the files on your computer's hard drive are arranged. This protocol isn't widely used anymore, but you can still find some operational gopher sites.

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You can connect to and use a remote computer program by using the telnet protocol. Generally you would telnet into a specific application housed on a serving computer that would allow you to use that application as if it were on your own computer. Again, using this protocol requires special software.

PACKETS

When two devices want to communicate across a LAN, one device will send a message to the other. This message is broken into chunks called packets. These packets are broadcast onto the LAN with the MAC address of the destination device. The destination device will see all of the traffic on the LAN but will only pick up the packets with it's own MAC address on them. It's a bit like getting your luggage back after a flight-you watch all the bags go round on the conveyer belt but you only pick up the bag with your name on it.
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Mac address

The MAC address is a unique value associated with a network adaptor. MAC addresses are also known as hardware addresses or physical addresses. They uniquely identify an adapter on a LAN.

MAC addresses are 12-digit hexadecimal numbers (48 bits in length).