COMPUTER NETWORKING CLASS 9

 

Computer networking

1.    Network- A network is the interconnection of various devices to share information and data.

2.    Computer network is a group of computers and other devices connected to each other to share data and information.

Types of Networks
There are mainly three types of networks as discussed below:
1. LAN (Local Area Network): It is a network that connects computers, mobile phones, tablet, mouse, printer, etc., placed at a limited distance. The geographical area covered by a LAN can range from a single room, a floor, an office having one or more buildings in the same premise, laboratory, a school, college, or university campus. The connectivity is done by means of wires, Ethernet cables, fiber optics, or Wi-Fi. LAN is comparatively secure as only authentic users in the network can access other computers or shared resources. Users can print documents using a connected printer, upload/download documents and software to and from the local server. . Such LANs provide the short range communication with the high speed data transfer rates. These types of networks can be extended up to 1 km. Data transfer in LAN is quite high, and usually varies from 10 Mbps (called Ethernet) to 1000 Mbps (called Gigabit Ethernet), where Mbps stands for Megabits per second
2. MAN (Metropolitan Area Network): This type of network spans a small city. Metropolitan Area Network (MAN) is an extended form of LAN which covers a larger geographical area like a city or a town. Data transfer rate in MAN also ranges in Mbps,

but it is considerably less as compared to LAN. Cable TV network or cable based broadband internet services are examples of MAN. This kind of network can be extended up to 30-40 km. Sometimes, many LANs are connected together to form MAN,

3.     WAN (Wide Area Network): This type of network spans an entire country and very often several countries. The speed of data transmission is a bit slower than that of LAN and the error rate is also high as the data has to travel over very long distances. Wide Area Network connects computers and other LANs and MANs, which are spread across different geographical locations of a country or in different countries or continents. A WAN could be formed by connecting a LAN to other LANs via wired/wireless media. Large business, educational and government organizations connect their different branches in different locations across the world through WAN. The Internet is the largest WAN that connects billions of computers, smartphones and millions of LANs from different continents.

Transmission/Communication Media- A transmission medium is a medium of data transfer over a network. It can be wired or wireless.

1 Twisted pair cable- In a twisted pair cable two wires are twisted together. The twisting of wires is done to minimize the electromagnetic interference of each other. A twisted pair cable can have up to eight twisted wires. These cables are also called Ethernet cables as these are commonly used in Ethernet networks at homes and offices.

·         Twisted pair cable is easy to install and maintain.

·         It involves less cost in installation than other cables.

·         There is reduced noise and crosstalk in this cable.

2. Coaxial cable – A coaxial cable consists of a copper wire at the center of the cable. A layer of plastic over the wire provides insulation and a metallic layer over the plastic reduces external interference.

A coaxial cable is used for long distance transmission such as in television and telephone networks, broadband internet connections and cable networks.

·         A coaxial cable has lesser signal interference than twisted pair cable

·         It can be used for a greater distance and more number of devices than the twisted pair.

·         It can carry higher frequency signals than the twisted pair cable.

4.       Optical Fiber cable – Optical fibers offer a very high bandwidth and this makes it capable of multichannel communication. it consists of multiple strands of glass or plastic fibre inside protective layers. This cable transmits data in the form of light instead of electronic signals. Hence there is nearly no electrical interference in this cable.

The optical fibre cable is more expensive than the coaxial cable and is used for high speed data transmission. It has the capacity to carry audio, video and data at extremely high speed. However, it is difficult to install and maintain an optical fibre as it is very fragile.

 

 

 

Tick (√) the correct option.

1. Which of the following transmission medium is the costliest?

a. UTP b. STP c. Coaxial Cable d. Optical Fibre

2. Which among the following is used for transmission in short range (mobile phone) devices?

 a. Infrared b. Bluetooth c. Coaxial Cable d. Optical Fibre

3. Which transmission would you use which can be setup at no time if the cost of digging the land for placing the cables is high?

 a. Microwaves b. Satellite Link c. Infrared Waves d. Bluetooth

 4. Which among the following protocol is used for transferring a web page from a web server to a web browser?

a. HTTP b. SMTP c. FTP d. TCP

5. Which of the following is not used for wired transmission?

a. Coaxial Cables b. Optical Fibre c. Twisted Pair Cable d. Microwaves

6. Which among the following protocols used for Internet Telephony?

 a. HTTP b. SMTP c. FTP d. VoIP  

7. What is the set of rules called that is used for transmission of data over a network?

a. LAN b. WAN c. Protocol d. Transmission Media

8. What is the practice of using a network of remote servers hosted on the Internet to store, manage, and process data, rather than a local server or a personal computer?

 a. Internet Computing b. Cloud Computing c. Protocol d. Transmission Media

9. Which among the following is not a type of cloud?

a. Public b. Private c. Protected d. Hybrid

10. A cloud is a mix of private and public cloud.

a. Public b. Private c. Protected d. Hybrid