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Class 8 Chapter 10 (Revision) Network and Communications Q1. What is networking? Ans. A network consists of two or more computers linked together for sharing resources through cables, telephone lines, waves, satellites or infrared light beams. Q2. What are the advantages and disadvantages of connecting computers in a network? Ans. ADVANTAGES 1. Speed.​ Networks​ provide a very rapid method for sharing and transferring files. 2. Cost.​ Besides monetary savings, sharing a program on a network allows for easier upgrading of the program. 3. ​Centralized Software Management​.​ All of the software can be loaded on one computer (the file server). 4. Resource​ Sharing. ​If costly peripherals are added to a network, they can be shared by many users. 5. Security​. Sensitive​ files and programs on a network are protected by passwords. DISADVANTAGES- 1. If the network stops operating then the computers connected to the network cannot be used. 2. As traffic increases on a network, the performance degrades. Q3. What is ? Ans- Internet is a “network of networks”. It is a global collection of high powered computers that are connected to each other with cables, telephone lines etc. and share the information with each other. Q6. Difference between LAN, MAN and WAN. 1. The geographical area covered by LAN is small, whereas, MAN covers relatively large and WAN covers the greatest of all. 2. LAN is confined to schools, or buildings, whereas, MAN connects small towns or Cities and on the other hand, WAN covers Country or a group of Countries. 3. Devices used for transmission of data are- LAN: WiFi, Cables. MAN: Modem and Wire/Cable WAN: Optic wires, Microwaves, Satellites. 4. LAN’s transmit data at a faster rate than MAN and WAN. 5. Maintenance of LAN is easier than that of MAN and WAN. 6. The available for transmission is higher in LAN than MAN and WAN. 7. Data transmission errors and noise are least in LAN, moderate in MAN and high in WAN. Q7. What is the difference between Client Server and Peer-to-Peer architecture? Ans- Peer-to-Peer Networks Client/Server Networks ​

1. Easy to set up 1.More difficult to set up 2. Less expensive to install 2. More expensive to install 3. More time consuming to maintain 3. Less time consuming to maintain the software being used the software being used (as most (as computers must be managed of the maintenance is managed individually) from the server) 4. Ideal for networks with less than 10 4. No limit to the number of Computers . computers that can be supported by the network 5. Does not require a server 5 Requires a server

Q8. What is a topology? Explain the different types of topologies used in computer networks. Ans- The physical arrangement of the cables, computers and other peripherals devices to form a network is known as a Topology. 1. BUS Topology

Features of Bus Topology 1. It transmits data only in one direction. 2. Every device is connected to a single cable Advantages of Bus Topology 1. Cable required is least compared to other . 2. Used in small networks. 3. Easy to expand joining two cables together. Disadvantages of Bus Topology 1. Cables fails then whole network fails. 2. If network traffic is heavy or nodes are more the performance of the network decreases. 3. It is slower than the ring topology. 2. RING Topology

Features of Ring Topology 1. The transmission is unidirectional, but it can be made bidirectional by having 2 connections between each Network , it is called ​Dual Ring Topology​. 2. In Dual Ring Topology, two ring networks are formed, and data flow is in opposite direction in them. Also, if one ring fails, the second ring can act as a backup, to keep the network up. Advantages of Ring Topology 1. Transmitting network is not affected by high traffic or by adding more nodes. 2. Cheap to install and expand Disadvantages of Ring Topology 1. Adding or deleting the computers disturbs the network activity. 2. Failure of one computer disturbs the whole network. 3. STAR Topology In this type of topology all the computers are connected to a single hub through a cable.

Features of Star Topology 1. Every node has its own dedicated connection to the hub. 2. Hub acts as a repeater for data flow. 3. Can be used with twisted pair, Optical Fibre or . Advantages of Star Topology 1. Fast performance with few nodes and low network traffic. 2. Hub can be upgraded easily. 3. Only that node is affected which has failed, rest of the nodes can work smoothly. Disadvantages of Star Topology 1. Cost of installation is high. 2. If the hub fails then the whole network is stopped. Q9. Explain the different types of Transmission Channels. Ans-In terminology, a is a physical path between the and the receiver i.e it is the channel through which data is sent from one place to another. Transmission Media is broadly classified into the following types:

Q10. Differences between Wired and transmission medium.

Ans- Wired Wireless 1. High Speed 1. Signal is broadcasted through air 2. Secure 2. Less Secure 3. Used for comparatively shorter 3. Used for larger distances distances Q11. Explain the different types of Wired transmission medium. Ans. 1. Twisted Pair Cable – Generally, several such pairs are bundled together in a protective sheath. They are the most widely used Transmission Media especially in telephone network. Twisted Pair is of two types: . 1. Unshielded Twisted Pair (UTP) 2. Shielded Twisted Pair (STP) 2. Coaxial Cable – It has an outer plastic covering containing 2 parallel conductors each having a separate insulated protection cover. Cable TVs and analog television networks widely use Coaxial cables.

3. Optical Fibre Cable – It uses the concept of reflection of light through a core made up of glass or plastic.It is used for transmission of large volumes of data. The cable can be unidirectional or bidirectional. Q12. Explain the different types of Wireless transmission medium. Ans. 1. Radiowaves – These are easy to generate and can penetrate through buildings.Frequency Range:3KHz – 1GHz. FM and cordless phones use Radiowaves for transmission. 2. Microwaves – Frequency Range:1GHz – 300GHz. These are majorly used for mobile phone communication and television distribution. 3. Infrared – Infrared waves are used for very short distance communication. Frequency Range: 300GHz – 400THz. It is used in TV remotes, wireless mouse, keyboard, printer, etc. 4. - Bluetooth is used to send and receive data over short distance in mobile and related technology. A Bluetooth connection is wireless and automatic.

5. Wi-Fi (Wireless Fidelity)​- This technology is basically used to establish Wireless LAN for providing wireless to the mobile users with the help of Wi-Fi hotspot, just like Bluetooth.

6. WiMax (Worldwide Interportability for Microwave Access)​- It is a long distance wireless communication system which uses high frequency microwaves to establish network connection. It is mainly used to provide broadband access to the user upto 50 kms for fixed devices and 5 to 15 kms for mobile devices. To establish this network there is a need of towers, like cell phones.