A network:
Is a group of two or more devices or people connected to each other so that they can exchange information, such as e – mail messages or documents or share resources such disk storage or printers.
Computer network:
Refers to collections of computing devices that are connected in various ways in order to communicate and share resources, usually the connections between computers in a network are made using physical wires or cables. However, some connections are wireless using radio waves or infrared signals.Networks are systems that are formed by links.The computers may be linked or connected to each other in the same building or different buildings. In most cases this connection is made via electrical cables that carry the information in the form of electrical signals. The cables transmitting the information are commonly known as transmission
Medias or Networking media.Networking media is the means by which signals or data are sent from one computer to another. The transmissions media are unshared Twisted Pair (UTP), coaxial cable and fiber optic cable. Whereas Wireless transmission media include radio waves, in folded and Bluetooth.When a computer is turned on and can be visible by all other computers then the computer is said to be online. If a computer is not turned on and it is not visible by other networked computers, it is then said to be offline.
Advantage of computer networks and communications
- Networks are all about sharing three things; Information , resources and applications
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- Sharing information
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Allow users to share information in several different ways. The most common way of sharing information is to share individual files. For example two or more people can work together on a word processing document
- Sharing resources
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Certain computer resources such as printers or hard drives can be set up so that network users can share them .sharing these resources can result in significant cost savings.
For example: it is cheaper to buy a single high – speed printer with advanced features that can be shared by an entire work group than to buy separate printers for each user in the group.
- Sharing applications:
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Several users can work together on a single business application. For example an accounting department may have accounting software that can be used from several computers at the same time (Database services)
- High reliability – All data can be copied on two or three machines so if one of them is unavailable then the other two copies could be used
- Speed – Network provides a very rapid method for sharing and transferring files. Without a network files are shared by coping them to flop disks, then carrying or sending the disk from one computer to another.
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4. Reduced cost: Net workable versions of many popular software programs are available at considerable savings when compared to buying
individual licensed copies. Bodies monetary saving, sharing a program on a network allows for easier upgrading of the program.
5. Sending messages such electronic mail (E- mail). The presence of a network provides the hardware necessary to install an E- mail
system. E- Mail aids in personal and professional communication for all school personnel, and it facilitates the dissemination of general
information to the entire school staff. Electronic mail on a LAN can enable students to communicate with teachers and peers at their own
school. If the LAN is connected to the internet, students can communicate with others throughout the world.
6. Flexible access: School network for example: allows students to access their files from computer throughout the school. Students can
begin an assignment in their classroom, save part of it on a public access area of the network, and then go to the media center after school to
finish their work. Students can also work cooperating through the network.
7. Communication : A computer network can provide a powerful communication medium a long widely separated employees or individual (increase communication capabilities)
Disadvantages of installing a Network
- Expensive to install: Although a network will generally save money, our time , the initial cost of installation can be prohibitive ; cable , network cards and software are expensive and the installation may require the services of a technician.
- Requires administrative time. Proper maintained of a network requires considerable time and expertise. Many schools have installed a network, only to find that they did not budget for the necessary administrative support.
- File server may fail: Although a file server is no more susceptible to failure than any other computer, when the files server “goes down” the entire network may come more to a halt. When this happens , the entire school or company may lose access to necessary programs and file
- Cables may break: Some of the configurations are designed to minimize the inconvenience of a Brocken cable, with other configurations; one Brocken cable can stop the entire network.
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What is Network
interface card?
- A network interface card (NIC) is a device that plugs into a mother board and provides ports for the network media connections.
- It is the component that interface with the local – area network (LAN)
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Example of NETWORK DEVICE
1) Switch
2) Bridge
3) Server
4) Fiber optic cable
5) Hub
6) Router
7) Twisted cable
8) Coaxial cable
9) Repeater