Networks

=media type="custom" key="3679379"media type="custom" key="3679327"= = = = = = = =Networks= A network is a group of two or more computers linked together so that they can share resources and can comunicated with one another A LAN is local area netword, where the computers are linked together and shares files and documents A WAN is Wide Area Network where the computers communicated with each other over telephone capables

LANs
Advantages of LANs Disadvantages of LANs
 * 1) It is cheap to implement
 * 2) Large number of users in the same domain
 * 1) Only users within a certain area radius can connect to the LAN.

Client Server Network Diagram

 * A client server network is a way to describe a relationship between two computer programs in which one program, the client program, makes a service request to another, the server program.

Peer to Peer Network Diagram

 * A peer to peer network is a network where all the computers are connected together, and every file and document is shared by the servers.

Cabled LANs

 * 1) Twisted pair is A copper caple, which is twisted in order to reduce the interferance of the signal
 * 2) Fibre optic is A cable that is made from a glass or plastic core that carries light surrounded by glass cladding that (due to its lower refractive index) reflects "escaping" light back into the core, resulting in the light being guided along the fibre. The outside of the fibre is protected by cladding and may be further protected by additional layers of treated paper, PVC or metal. This required to protect the fibre from mechanical deformation and the ingress of water.
 * 3) NIC is A network interface card is used to connect a computer to an Ethernet network. The card provides an interface to the media. this may be either using a transcevier or through an internal intergrated transciver mounted on the network interface card PCB. the card usually contains the protocol control firmware and Ethernet controller needed to support the medium access control data link protocol used by Ethernet.

BUS Network Diagram
Advantages Disadvantages
 * 1) Easy to install
 * 2) Easy to add extra workstations
 * 3) Best choice for temporary networks
 * 4) Extending the network is very easy. New erquipment can be connected to it by simply attaching it to the end of the network or adding a short spur
 * 5) Only a single network cable needs to be installed
 * 1) If there is problem, the entire network stops working
 * 2) Low security-every workstation can see all of the data in the network.
 * 3) Any problem with the mains cable may cause the whole network to malfunction
 * 4) Data travels in both directions along the network cable so that packets of data may collide. This may slow down the transmission speed and data may be lost

Star Topology Diagram
Advantages
 * extending the network is very straightforward. New equipment can be connected to it simply by connecting it to the server.
 * if one computer stops working the network is not affected.
 * if a cable stops working, only one computer is affected.

Disadvantages
 * it requires more cabling as each computer has it's own cableto the hub.
 * it may be more difficult to connect a new computer to the network as a seperate cable is needed from the computer to the server.
 * a star network topology requires more cable than a line network.

Ring Network Diagram
Advantages
 * transmission of data is fairly simple as it only travels in one direction
 * no data collisions
 * extra computers can be added easily with little effect on on performance although you have to shut down the network to be able to do this.

Disadvantages
 * if a single machine is switched off, the network doesn't work
 * if a cable breaks, the network doesn't work
 * data must pass through every computer until it reaches its destination. This can make it slower than other network layouts
 * if there are any problems with the network, they can be difficult to identify the cause.

Network Transmission

 * Bandwidth is the amount of data the computer is able to take in
 * Broadband is similar to a modem but instead of a telephone line it uses fibre optical cables

Modem Diagram
**The Internet is** A world-wide network of computers linked by telephone lines, allowing for information to travel. A router is ** something that allows for network communication to take place between a computer WWW is ** World Wide Web
 * An ISP is**- internet service provider, An organization offering and providing Internet access to the public
 * TCP/IP is** is a set of protocols used to transfer data from one computer to another
 * A browser is** a program used to view HTML documents
 * [[image:http://tbn0.google.com/images?q=tbn:lsAAWNEhsoj0MM:http://abcdefu.files.wordpress.com/2008/06/firefox.jpg width="122" height="118" link="http://images.google.com/imgres?imgurl=http://abcdefu.files.wordpress.com/2008/06/firefox.jpg&imgrefurl=http://abcdefu.wordpress.com/2008/06/14/quickstart-to-creating-firefox-extensions/&usg=__5WwGY9LvffZPYSg5MXwNtHFLFuc=&h=356&w=369&sz=31&hl=en&start=1&sig2=gY4yKq1cyiMRjBPUEnXOsQ&um=1&tbnid=lsAAWNEhsoj0MM:&tbnh=118&tbnw=122&ei=Zgu2SenANYKg6gPop6ClCQ&prev=/images%3Fq%3Dfirefox%26hl%3Den%26um%3D1%26newwindow%3D1"]]
 * [[image:http://tbn3.google.com/images?q=tbn:dBCriU7EVtLGjM:http://www.slipperybrick.com/wp-content/uploads/2007/09/linksys-wrt100-rangeplus-router.jpg width="129" height="130" link="http://images.google.com/imgres?imgurl=http://www.slipperybrick.com/wp-content/uploads/2007/09/linksys-wrt100-rangeplus-router.jpg&imgrefurl=http://www.slipperybrick.com/2007/09/linksys-rangeplus-networking/&usg=__7SZK8n1VnOb4IR1CDT4d_oel-tU=&h=505&w=500&sz=26&hl=en&start=1&sig2=0qNt7KzKMXjDUBeeJQcBwQ&um=1&tbnid=dBCriU7EVtLGjM:&tbnh=130&tbnw=129&ei=fgu2SfWsB5Wm6wPr7rCZCQ&prev=/images%3Fq%3Drouter%26hl%3Den%26um%3D1%26newwindow%3D1"]]
 * **Hypertext is** a document that conains a hyperlink to another document on the same or another computer
 * **A hyperlink** allows you to move easilly from from one place to another through a link created on an object

__Advantages__

 * 1) It can use anywhere and anytime.
 * 2) Don't have to travel long distances.
 * 3) Individuals living in remote areas can also use video conferencing to keep in touch with the outside world.
 * 4) Technology information and knowledge are often disseminated at more rapid rates.
 * 5) Much more personal.

__Disadvantages__

 * Time consuming to set it up.
 * Expensive Equipments.
 * Requires at least 2 locations with equipments set up.
 * Video equipment investment can be stranded during every day normal use of conference rooms for local meetings.
 * Extra funds are needed to ensure each endpoint is staffed with a skilled technician.


 * FTP is a File Transfer Protocol for exchanging and manipulating files over a TCP ( Transmission Control Protocol ) computer network.
 * Spam is unsolicited ( not asked ) or undesired email messages.
 * A firewall is an integrated collection of security measures designed to prevent unauthorized access to an information system or network.
 * Parental control software is a software which allows a parent to monitor or limit what a child can see or do and/or time-limit these activities.
 * Hacking is using unauthorized methods to bypass the security mechanisms of an information system or network.
 * Piracy is selling or using somebody elses copyrighted copy and using it without permission.