RBSE Solutions Class 9 Information Technology Chapter 3 Computer Communication and Network

Textbook Questions Solved

I. Multiple Choice Questions

Question 1. Which one is the oldest one and mostly used device in communication medium-
(a) Coaxial cable
(b) Optical Fiber
(c) Twisted pair
(d) None of the options
Answer: (c) Twisted pair
In simple words: Twisted pair cables are like old telephone wires. They have been used for a very long time to send messages because they are simple and work well over short distances.

🎯 Exam Tip: Remember that "Twisted pair" is often associated with older, simpler network setups, while "Optical Fiber" is known for speed and modernity.

Question 2. What do you mean by WAN?
(a) Wire area network
(b) Wire accessible network
(c) Widely accessible network
(d) Wide Area Network
Answer: (d) Wide Area Network
In simple words: WAN stands for Wide Area Network. It means a computer network that covers a very large area, like across cities or countries.

🎯 Exam Tip: When dealing with acronyms, always know the full form to understand the concept correctly. WAN, LAN, and MAN are common network types.

Question 3. Which one is the fastest communication medium?
(a) Twisted pair
(b) Coaxial cable
(c) Optical Fiber
(d) Cellular Phone
Answer: (c) Optical Fiber
In simple words: Optical fiber is the fastest way to send information. It uses light signals through thin glass strands, which moves much quicker than electricity in copper wires.

🎯 Exam Tip: Optical fiber's speed comes from its use of light for data transmission, making it superior for high-bandwidth and long-distance communication.

Question 5. What is the name of Glass Core surrounding on Optical Fiber?
(a) Yok
(b) Clad
(c) Cap
(d) Pipe
Answer: (b) Clad
In simple words: The glass core of an optical fiber is surrounded by a layer called cladding. This cladding helps to keep the light inside the core so it can travel long distances.

🎯 Exam Tip: The cladding is crucial for the internal reflection of light within the fiber, preventing signal loss. Don't confuse it with a simple protective layer.

Question 6. In which communication medium, waves are spread in all sides
(a) Radio Link
(b) Micro wave
(c) Infrared
(d) Satellite
Answer: (a) Radio Link
In simple words: In a radio link, signals spread out in all directions from the antenna. This allows many receivers to pick up the signal at once.

🎯 Exam Tip: Radio waves are omnidirectional, meaning they can spread in many directions, which is why they are used for broadcasting to a wide audience.

Question 7. How many minimum satellite communication medium need to send signals to earth
(a) two
(b) three
(c) four
(d) five
Answer: (b) three
In simple words: At least three satellites are needed for continuous global communication. This ensures that a signal can always reach an earth station, even as the earth rotates.

🎯 Exam Tip: Three geostationary satellites, spaced evenly, can provide nearly full coverage of the Earth's surface for uninterrupted communication.

Question 9. A computer network which is used for communication among computers and their peripherals in small area to each other is called
(a) LAN
(b) MAN
(c) WAN
(d) None of the options
Answer: (a) LAN
In simple words: A network that connects computers and devices within a small area, like a home, office, or school, is called a Local Area Network (LAN).

🎯 Exam Tip: Distinguish between LAN (Local Area Network), MAN (Metropolitan Area Network), and WAN (Wide Area Network) based on the geographic size of the network.

Question 10. Which one is the communication medium
(a) Modem
(b) Hub
(c) Bridge
(d) None of the options
Answer: (a) Modem
In simple words: A modem is a device that helps computers connect to the internet over telephone lines or cable. It changes digital computer signals into analog signals that can travel over these lines.

🎯 Exam Tip: A modem (modulator-demodulator) is essential for converting digital data into a format suitable for transmission over various communication lines.

II. Very Short Answer Type Questions

Question 1. Which one is the oldest and most commonly used communication medium?
Answer: Twisted pair.
In simple words: Twisted pair cables are the oldest and most used way to send information, especially in phone lines.

🎯 Exam Tip: When asked about the oldest medium, consider the history of telecommunications; twisted pair has been fundamental for a long time.

Question 2. What is extended form of WAN?
Answer: Wide Area Network.
In simple words: WAN simply means Wide Area Network, covering large geographical areas.

🎯 Exam Tip: Always remember the full forms of common network acronyms like LAN, WAN, and MAN as they are frequently asked in exams.

Question 4. What is the name of core surrounding on OFC?
Answer: Cladding.
In simple words: The core of an Optical Fiber Cable (OFC) is surrounded by a layer called cladding. This layer helps guide light within the fiber.

🎯 Exam Tip: The cladding is crucial in optical fibers for maintaining total internal reflection, which keeps the light signal contained within the core.

Question 5. What is significance of Repeater?
Answer: To regenerate signals.
In simple words: A repeater makes signals strong again. This is important because signals can get weak when they travel long distances.

🎯 Exam Tip: Repeaters are vital in communication networks to extend the range of signals by boosting and cleaning them up before retransmission.

Question 6. At which height a Satellite communication medium is installed?
Answer: 36000 KM.
In simple words: Communication satellites are usually placed at a height of 36,000 kilometers above the Earth. This specific height is called geostationary orbit.

🎯 Exam Tip: Geostationary orbit (around 35,786 km) is key for communication satellites, as it allows them to stay above the same point on Earth, providing continuous coverage.

Question 7. What is extended form of WIFI?
Answer: Wireless Fidelity
In simple words: WIFI stands for Wireless Fidelity, which is a technology that lets you connect to the internet without cables.

🎯 Exam Tip: While commonly used, understanding that "Wireless Fidelity" is the full term for Wi-Fi can help you grasp its core function of reliable wireless connection.

Question 8. Which device is used to convert Analog signal to Digital signal and Digital signal to Analog signal?
Answer: MODEM.
In simple words: A modem converts analog signals to digital and vice versa. This allows computers to send data over regular phone lines.

🎯 Exam Tip: The term MODEM is short for Modulator-Demodulator, directly reflecting its function of converting signals for transmission.

Question 9. Which network is used to cover a big town?
Answer: Metropolitan Area Network.
In simple words: A Metropolitan Area Network (MAN) is used to connect computers and devices over a large city or campus.

🎯 Exam Tip: Remember MAN for city-wide coverage, sitting between the smaller LAN and the much larger WAN in terms of geographical scope.

Question 10. In which topology, nodes are connected in Hierarchical manner?
Answer: Tree Topology.
In simple words: In a tree topology, computers are arranged like a branching tree. They are connected in levels, with a main cable and smaller branches.

🎯 Exam Tip: Tree topology is basically a combination of bus and star topologies, creating a hierarchical structure suitable for larger networks.

Question 2. What is cross-talk?
Answer: Crosstalk is a disturbance that happens when signals from one communication line accidentally affect a nearby line. For example, in a phone call, you might faintly hear part of another conversation. This occurs because electric or magnetic fields from one wire interfere with the signal in another wire nearby.
In simple words: Crosstalk is when you hear sounds or signals from one conversation or line bleeding into another. It's like a signal mixing with a nearby signal.

🎯 Exam Tip: Crosstalk is an important concept in signal integrity; it represents unwanted coupling between communication channels and can degrade signal quality.

Question 3. Where coaxial cable is used?
Answer: Coaxial cable is used to send radio frequency signals. It is commonly used for connecting computers to networks, especially for internet connections. It is also used to distribute cable television signals and for digital audio connections. The cable design helps keep signals strong and clear.
In simple words: Coaxial cables are used for things like internet and cable TV. They send radio signals and keep them strong.

🎯 Exam Tip: Coaxial cables are valued for their shielding properties, which help prevent interference and maintain signal quality over moderate distances.

Question 4. What are the uses of Bluetooth?
Answer: Bluetooth is a wireless technology that allows devices like computers, phones, and others to connect over short distances, usually up to 100 meters. It uses radio waves to create secure and affordable connections without wires. Bluetooth is used in many ways, such as sending photos from a mobile phone, exchanging contact information, and using wireless headsets with phones. It can also be used for real-time satellite navigation systems. This technology makes connecting devices simple and convenient.
In simple words: Bluetooth connects devices without wires for short distances. You can use it to send files, connect headphones, or share information easily.

🎯 Exam Tip: Highlight Bluetooth's short-range wireless communication ability and its role in connecting personal devices like headphones, phones, and smartwatches.

Question 5. Why microwave is put on very High distance?
Answer: Microwaves are used for point-to-point communication over long distances because their small wavelength allows antennas to send them in narrow, focused beams. This prevents interference with other nearby microwave equipment using the same frequencies. Another benefit is that the high frequency of microwaves allows them to carry a lot of information. This makes them ideal for long-distance data transfer. However, microwaves are limited to line-of-sight communication and cannot easily pass through obstacles.
In simple words: Microwaves are good for long-distance communication because they can be sent in focused beams, carrying lots of information without mixing with other signals. They need to travel in a straight line, so they are often placed high up.

🎯 Exam Tip: Emphasize line-of-sight transmission for microwaves and their capacity for high data rates due to high frequencies, making them suitable for long-distance, focused communication links.

Question 7. Gives any two characteristics of LAN.
Answer: LAN has the following characteristics:
1. The coverage area is generally a few kilometers, meaning it covers a small geographic space like an office or building.
2. LANs can achieve high transmission rates, typically from 1 Mb/s up to 100 Mb/s or even higher with newer technology. These speeds allow for quick data transfer within the network.
3. In a LAN, you can connect multiple devices to share a single transmission medium, making resource sharing efficient.
4. LANs commonly use bus and ring topologies to arrange their connected devices.
In simple words: A LAN covers a small area like an office and sends data very fast. It helps many devices share things like printers.

🎯 Exam Tip: Focus on the small geographical area and high data transfer speeds as primary characteristics distinguishing LANs from other network types.

Question 8. What are the characteristics of nodes in star topology?
Answer: Characteristics of nodes in star topology:
1. Compared to bus topology, star topology offers much better performance because signals don't have to travel to all workstations. A signal reaches its intended destination after passing through only a few devices. The network's performance depends on the central hub's capacity.
2. It's easy to connect new nodes or devices in a star topology without affecting the rest of the network. Similarly, components can be removed easily.
3. Star topology allows for centralized management, which helps in monitoring the network.
4. If one node or link fails, it does not affect the rest of the network. It's also easy to detect and fix such failures quickly. The central hub is critical for all communication.
In simple words: In a star network, all computers connect to a central hub. It's easy to add or remove computers, and if one computer breaks, the others keep working.

🎯 Exam Tip: Remember that the star topology's key strength is its centralized management and fault isolation, meaning a single node failure doesn't bring down the whole network.

Question 10. What is difference between Switch and Hub?
Answer: A Hub is a networking device that connects multiple computers to a single network, typically based on Ethernet, Firewire, or USB. It is an electronic device that connects many network devices, allowing them to exchange data. A Hub sends data to *all* connected devices. On the other hand, a network switch is a computer networking device that connects multiple devices on a computer network. A switch is more advanced than a hub because it sends messages *only* to the specific device that needs or requests it. This makes network communication more efficient and secure. The switch acts like a smart control unit for data flow.
In simple words: A hub sends all data to every device connected to it, like shouting in a room. A switch is smarter; it sends data only to the specific device that needs it, like whispering to one person.

🎯 Exam Tip: The fundamental difference lies in how they handle data traffic: hubs broadcast to all ports, while switches intelligently direct traffic to specific destinations, improving network efficiency.

IV. Long Answer Type Questions

Question 1. What is the basic structure of Optical fiber? Also explain working of optical fiber.
Answer: The basic structure of an optical fiber has three main parts: the core, the cladding, and the coating or buffer. The core is a cylindrical rod made of dielectric material, which means it does not conduct electricity. Light signals travel mainly through this core. It's typically made of glass and has a specific refractive index. Surrounding the core is the cladding, another layer of material with a lower refractive index than the core. While light can travel without cladding, the cladding is important because it prevents light from escaping the core into the surrounding air and reduces scattering loss at the core's surface. It also protects the fiber from contaminants and adds mechanical strength. For extra protection, an additional layer called the coating or buffer encloses the cladding. This buffer, usually made of plastic, protects the optical fiber from physical damage and abrasions. It also helps prevent light scattering losses caused by microbends, which are tiny bends or distortions in the fiber.
In simple words: An optical fiber has a core for light to travel, surrounded by cladding that keeps the light inside. An outer coating protects the fiber from damage. Light travels through the core by bouncing off the cladding, which guides it along.

🎯 Exam Tip: When describing optical fiber, always mention the core, cladding, and buffer, and explain how the difference in refractive index between the core and cladding enables total internal reflection for light transmission.

Question 2. What is a Computer Network? Uses of Computer Networks.
Answer: A computer network is created when multiple computers are connected to each other. These connections allow them to share software, hardware, and data using a communication medium. Computers within a network can share files, folders, applications, and resources like scanners, webcams, and printers. The internet is the most common example of a computer network, connecting millions of devices worldwide. A computer network is essentially a group of independent computers that enable distributed processing of information and data, which helps in increasing communication and resource sharing. To set up a network, you need a sender, receiver, a communication channel, protocols (rules for communication), and an operating system. This structure allows devices to work together efficiently. The computer networks are useful to organizations in the following ways:
1. Resource sharing: Networks allow users to share printers, scanners, and other hardware, as well as software applications and data.
2. High reliability: By connecting multiple computers, data can be stored on different machines. If one computer fails, the data can still be accessed from another, providing high reliability.
3. Cost saving: Sharing resources like printers and internet connections among many users reduces the overall cost.
4. Powerful communication medium: Networks provide effective tools for communication, such as email, instant messaging, and video conferencing, which help people stay connected and work together.
In simple words: A computer network connects many computers so they can share things like files, printers, and internet access. This helps people work together, save money, and access information more easily. The internet is a huge computer network.

🎯 Exam Tip: For computer networks, remember the core idea: sharing resources (hardware, software, data) to improve communication and efficiency, with the Internet as the prime example.

Question 3. What is Network Topology? Explain various types topology.
Answer: Network topology refers to the way different components of a network, such as nodes, links, and peripherals, are arranged. It defines the physical and logical structure or shape of the network. Physical topology describes the actual layout of computers, workstations, and cables in the network, while logical topology explains how information flows between these components. In simpler terms, physical topology is about how things are wired, and logical topology is about how data moves. Physical topology usually relates to the main network structure, and logical topology relates to the basic network. There are five main types of Physical Network Topologies:
1. Bus Topology
2. Star Topology
3. Ring Topology
4. Mesh Topology
5. Tree Topology

(i) Bus Topology:
Advantages:
* It is easy to set up and expand the bus network.
* This topology needs the least amount of cable compared to other networks, which makes it less expensive.
* Bus topology costs very little to implement.
* A linear bus network is most commonly used in smaller networks, making it good for Local Area Networks (LANs).

(ii) Star Topology:
Advantages:
* Compared to a bus topology, a star topology provides much better performance. Signals don't necessarily have to be sent to all workstations.
* A signal reaches its intended destination after passing through only a few devices, making communication efficient. The network's overall performance depends on the central hub's capacity.
* New nodes or devices can be easily connected in a star topology without affecting the rest of the network. Similarly, components can also be removed with ease.
* It provides centralized management, which helps in monitoring the network.
* If one node or link fails, it does not affect the rest of the network. At the same time, it is easy to detect the failure and troubleshoot it.

(iii) Ring Topology:
Advantages:
* This type of network topology is very organized. Each node can send data only when it receives an empty "token," which helps reduce data collisions.
* In ring topology, all traffic flows in only one direction at very high speed.
* Even when the network load increases, its performance is better than that of bus topology.
* There is no need for a network server to control connectivity between workstations.
* Adding new components does not affect the network's performance.
* Each computer in the network has equal access to resources.

(iv) Mesh Topology:
Advantages:
* Data can be transmitted simultaneously between different devices. This topology can handle high traffic.
* Even if one component fails, there is always an alternative path for data transfer, so communication is not affected.
* Expanding and modifying the topology can be done without disturbing other nodes.

(v) Tree Topology:
Advantages:
* This topology extends star and bus topologies, making it a good choice for networks that need to scale but can't use star or bus individually.
* Expanding the network is easy.
* The entire network is divided into segments (like star networks), which are easy to manage and maintain.
* Error detection and correction are simple.
* Each segment has dedicated point-to-point wiring to its central hub.
* If one segment is damaged, other segments are not affected.
In simple words: Network topology is how computers are arranged in a network. There are different types like Bus, Star, Ring, Mesh, and Tree. Each has its own way of connecting computers and sharing information, with different advantages for speed, reliability, and how easy it is to set up.

🎯 Exam Tip: For network topologies, focus on understanding the diagram of each type, its central concept (e.g., central hub in star, shared cable in bus), and its main advantages/disadvantages, especially regarding fault tolerance and scalability.

Additional Questions Solved

I. Multiple Choice Questions

Question 1. What is the extended form of WiFi? types of network cards.
(a) Wireless Function
(b) Wireless Fidelity
(c) Wireless Fiction
(d) Wireless Fields
Answer: (b) Wireless Fidelity
In simple words: WiFi stands for Wireless Fidelity, which is the full name for the wireless internet connection we use every day.

🎯 Exam Tip: While often just called Wi-Fi, knowing the full form "Wireless Fidelity" helps solidify your understanding of its purpose: reliable wireless connection.

Question 2. Which one is not an example of physical network topologies?
(a) Train Topology
(b) Bus Topology
(c) Tree Topology
(d) Star Topology
Answer: (a) Train Topology
In simple words: "Train Topology" is not a real type of network arrangement. Bus, Tree, and Star are actual ways computers are connected in a network.

🎯 Exam Tip: Be familiar with the standard network topologies (Bus, Star, Ring, Mesh, Tree) to easily identify an incorrect or fictitious option.

II. Very Short Answer Type Questions

Question 1. Name one of the hardware required to setup a computer network.
Answer: Network cables are a key hardware component needed to set up a computer network. These cables allow different devices to connect and share information.
In simple words: You need network cables. They help computers talk to each other.

🎯 Exam Tip: When asked for hardware, remember common connection components like cables or routers.

Question 2. Give the types of internal network cards.
Answer: The main types of internal network cards are Peripheral Component Interconnect (PCI) and Industry Standard Architecture (ISA) cards. These cards are fitted inside a computer to connect it to a network.
In simple words: Internal network cards are mostly of two types: PCI and ISA. They help your computer connect to a network from inside.

🎯 Exam Tip: Remember the full names for PCI and ISA as they are common abbreviations in networking.

Question 4. USB cards are connected through which points?
Answer: USB cards connect to a computer through a USB port. This type of connection is widely used for many external devices.
In simple words: USB cards connect using a USB port. This is how many devices plug into a computer.

🎯 Exam Tip: Always specify 'USB port' when talking about connections for USB devices.

Question 5. In which parts, basic structure of an optical fibre is divided?
Answer: The basic structure of an optical fiber is divided into three main parts. These parts work together to guide light for data transmission.
In simple words: An optical fiber has three main parts. They help send light signals.

🎯 Exam Tip: Remember that optical fibers have three key parts: the core, cladding, and buffer.

III. Short Answer Type Questions

Question 1. What is a computer network? Also, give two characteristics.
Answer: A computer network is a system where many computers are linked together. This connection allows them to communicate and share data. Two important features of a computer network are:
1. It allows users to share resources, like printers or internet access, from one computer with another.
2. It makes it possible to create files on one computer and then open or use those same files from other computers connected to the network.
In simple words: A computer network connects many computers so they can talk to each other. It helps them share things like printers and also lets you use files from any computer on the network.

🎯 Exam Tip: When defining a network, highlight both connection and resource sharing. For characteristics, focus on tangible benefits.

Question 2. List some of the hardwares required to setup a computer network.
Answer: To set up a computer network, you need several hardware components. These include:
1. Routers: Devices that direct data traffic between networks.
2. Network cables: Physical wires that connect devices.
3. Internal network cards: Cards installed inside computers for network connectivity.
4. External network cards: Devices that plug into a computer externally for network access (like USB Wi-Fi adapters).
In simple words: To make a computer network, you need hardware like routers, network cables, and network cards (both inside and outside the computer).

🎯 Exam Tip: List at least three distinct hardware items and briefly explain their role if time permits.

Question 3. What is a Router?
Answer: A router is a special networking device that finds the best path for data packets to travel between different computer networks. It keeps a list of available routes and uses this information to send data to its correct destination. Routers work at the network layer, which is layer 3 of the OSI model.
In simple words: A router is like a traffic controller for network data. It helps send information packets on the best path from one network to another, making sure they reach the right place.

🎯 Exam Tip: Emphasize that a router connects different networks and directs data traffic based on optimal paths.

Question 4. Define centralized computing system.
Answer: A centralized computing system, also known as client-server computing, connects many computers to a single main computer, often called a mainframe or server. In this setup, the smaller computers, called 'clients' or 'nodes', only connect to the central server and rely on it for processing and data storage.
In simple words: Centralized computing means many small computers connect to one big main computer. The small computers are called clients, and they all rely on the big server for their work.

🎯 Exam Tip: Key terms to use are 'client-server computing' and the idea of multiple clients connected to a single central server.

Question 5. Explain any one physical network topology?
Answer: One example of a physical network topology is the 'Bus' topology. In this setup, all computers connect to a single main cable, called the bus. It is simple to install and expand. Bus topology needs the least amount of cable compared to other layouts, which makes it less costly. This linear structure is often used for smaller networks.
In simple words: Bus topology is a network layout where all computers connect to one main cable. It is easy to set up, needs less cable, and is good for small networks.

🎯 Exam Tip: When explaining a topology, describe its basic structure, mention an advantage, and state where it is typically used.

IV. Long Answer Type Questions

Question 1. What is a network card? Also, explain its types.
Answer: A network card, also known as a network adapter or Network Interface Card (NIC), is a crucial hardware part of a computer that allows it to connect to a network. Without it, a computer cannot communicate with other devices on a network. Most modern computers come with a network card already built-in.
There are two main types of network cards:
1. **Internal Network Cards:** These cards fit into special slots on the computer's motherboard. They often require network cables to connect to the network. Common types include Peripheral Component Interconnect (PCI) and Industry Standard Architecture (ISA) cards.
2. **External Network Cards:** These cards are connected to the computer from the outside. They are typically wireless (like Wi-Fi adapters) or USB-based. External wireless cards allow network connection without physical cables, while USB-based cards plug into a USB port.
In simple words: A network card helps a computer connect to a network. Without it, computers cannot talk to each other. There are two types: internal cards that go inside the computer, and external cards that plug in from outside, like USB or wireless ones.

🎯 Exam Tip: Clearly define the network card and then differentiate between internal and external types, providing examples for each.