Question 1

Question 1Assertion (A): ARPANET was the first computer network created in the year 1969 by Advanced Research Projects Agency (ARPA) of the Pentagon, USA.Reasoning (R): The objective of creating ARPANET was to develop a reliable communication network for the US military defence services for sending and receiving instant messages.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationARPANET, jointly designed and named by the Advanced Research Projects Agency (ARPA) and the US Department of Defense (DoD), was the first computer network and came into existence in 1969. The objective of creating ARPANET was to develop a reliable communication network for the US military defense services, enabling them to send and receive instant messages and share data.

Question 2

Question 3Assertion (A): A PAN (Personal Area Network) is established within the vicinity of a room (20 to 30 sq.ft.) for sharing information with the computers.Reasoning (R): A WAN (Wide Area Network) spans thousands of kilometres and is used to establish connectivity across several countries and continents.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.ExplanationPANs (Personal Area Networks) are small networks used to establish communication between a computer and other devices in proximity, typically up to 10 meters (20 to 30 sq.ft.). On the other hand, a WAN (Wide Area Network) spans a large geographical area across countries and continents. A WAN can cover an area with a radius spanning hundreds of kilometers.

Question 3

Question 4Assertion (A): A Repeater is a device that amplifies the network over geographical distance.Reasoning (R): A Hub is a device which is used to connect more than one device in the network.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true but R is not the correct explanation of A.ExplanationA repeater is a device that amplifies a signal transmitted across the network so that the signal is received in the same way it is sent. A hub is a hardware device used to connect several computers together using different ports.

Question 4

Question 5Assertion (A): VoIP stands for Voice over Internet Protocol.Reasoning (R): VolP is a technology that allows us to make voice calls using a broadband connection instead of a regular phone line.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Both A and R are true and R is the correct explanation of A.ExplanationVoIP stands for Voice over Internet Protocol, and it is a technology that allows us to make voice calls using a broadband connection instead of a regular phone line. The voice calls are first digitized, compressed, and then fragmented into small packets, which are then relayed by Internet Protocol (IP) across the network.

Question 5

Question 7Assertion (A): Infrared (IR) is a wireless technology used for data communication.Reasoning (R): Infrared involves the usage of electromagnetic radiation whose wavelength is shorter than the visible light but can penetrate easily through walls and obstacles; thus, it is used where there is an obstacle between two devices under communication.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

A is true but R is false.ExplanationInfrared (IR) is a wireless technology used for data communication. Infrared involves the usage of electromagnetic radiation, specifically infrared light, to send data. The data is transmitted through the air and can propagate in open space; however, it cannot penetrate the walls of a room and is affected by distance, noise, and heat. It is an example of a short-range wireless network.

Question 6

Question 6Write short notes on the following:(a) Bandwidth(b) Bluetooth(c) DNS(d) Data transfer rate(e) HTTP

Accepted Answer

(a) Bandwidth — Bandwidth of a channel is the range of frequencies available for the transmission of data through that channel. The higher the bandwidth, the higher the data transfer rate. Bandwidth is calculated as the difference between the maximum and minimum frequencies contained in the composite signals, and it is measured in Hertz (Hz).(b) Bluetooth — Bluetooth is a short-range wireless technology used to connect devices like mobile phones, mouse, headphones, keyboards, and computers wirelessly over short distances. It enables tasks such as printing documents with Bluetooth-enabled printers without the need for physical connections. These devices utilize a low-cost transceiver chip that operates within the unlicensed frequency band of 2.4 GHz for data transmission and reception. Bluetooth devices can communicate within a range of 10 meters, achieving speeds of 1-2 Mbps. The technology allows up to 255 devices to form a network, with 8 devices capable of simultaneous communication while others remain inactive until prompted by the master device.(c) DNS — DNS, known as the Domain Name System, serves as the phonebook of the Internet. It provides a character-based naming system for servers, allowing users to access websites using easy-to-remember domain names like google.com instead of numeric IP addresses such as 8.8.8.8. DNS is essential for internet navigation as it translates domain names into IP addresses, enabling seamless communication and resource access across the web.(d) Data transfer rate — Data transfer rate is the number of bits transmitted between source and destination in one second. It is also known as bit rate. It is measured in terms of bits per second (bps). The higher units for data transfer rates are: 1 Kbps = 210 bps = 1024 bps 1 Mbps = 220 bps = 1024 Kbps 1 Gbps = 230 bps = 1024 Mbps 1 Tbps = 240 bps = 1024 Gbps(e) HTTP — HTTP stands for HyperText Transfer Protocol, which is the primary protocol used to access the World Wide Web. It is a request-response protocol (also called client-server) that runs over TCP. HTTP facilitates access to hypertext from the World Wide Web by defining how information is formatted and transmitted, and how web servers and browsers should respond to various commands.For example, whenever we enter the URL http://www.ncert.nic.in in a browser, it sends an HTTP request to the web server where ncert.nic.in is hosted. The HTTP response from the web server fetches and sends the requested web page, which is then displayed on the browser.

Question 7

Question 8Draw a network layout of star topology and bus topology connecting five computers.

Accepted Answer

Star TopologyBus Topology

Question 8

Question 9Rohit, a Class XI student, has just started understanding the basics of internet and web technologies. He is a bit confused about the terms "World Wide Web" and "Internet". Help him understand both the terms with the help of suitable examples of each.

Accepted Answer

The World Wide Web (WWW) is a set of protocols that allows us to access any document on the Net through a naming system based on URLs. The WWW also specifies a way, known as the Hypertext Transfer Protocol (HTTP), to request and send hypermedia documents over the Internet.The Internet is a worldwide network of computer networks that allows all computers to exchange information with each other. They follow protocols like TCP/IP (Transmission Control Protocol/Internet Protocol) for communication.The WWW is a small part of the Internet. We can say that the Internet is a highway that offers many services and features, and the WWW is a vehicle (like a truck) that uses this highway to transport information.

Question 9

Question 10Describe bus topology and star topology.

Accepted Answer

Bus topology — Bus topology is a multi-point configuration, i.e., several devices are connected to a main long cable (usually co-axial cable) which acts as a backbone. Nodes are connected by drop lines and taps. A drop line is a connection between long cable and devices and taps are the connectors that are punctured inside the main cable. The data flows from one end of the cable to the other. The cable has terminators at both ends which absorb signals when the signal reaches the end, preventing signal bounce. However, as the signal travels a long distance, it becomes weaker and weaker. It works well for small networks.Star Topology — In star topology, each communicating device is connected to a central controller called a hub or switch. The devices in star topology send and receive data indirectly, the data passes to and from the hub. The central node can be either a broadcasting device (hub) or a unicast device (switch).

Question 10

Question 11Define the following terms:(a) Baud(b) Communication channel(c) Hub(d) Repeater

Accepted Answer

(a) Baud — Baud refers to the number of discrete signal elements transmitted per second. It is the measuring unit of the data transfer rate.(b) Communication channel — Communication channel is also known as transmission media through which data or signal is transferred between two communicating devices, i.e., from one system to another system, through wires or without wires.(c) Hub — A hub is a networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together.(d) Repeater — A repeater is a device that amplifies a signal transmitted across the network so that the signal is received in the same way it is sent.

Question 11

Question 12What is modem? Define the functioning of internal modem and external modem.

Accepted Answer

A MODEM (Modulator Demodulator) is an electronic device that enables a computer to transmit data over telephone lines. It is a device used to convert digital signals into analog signals and vice versa.The functioning of internal modem and external modem is as follows:Internal modem — These are attached to the internal slot of the motherboard. They modulate digital data into analog signals for transmission and demodulate incoming analog signals into digital data.External modem — It is a small box connected to the communication port of the computer. It works similarly to the internal modem. The only difference is that it is placed outside the CPU box.

Question 12

Question 13Expand and explain the following terms:(a) PPP(b) POP3(c) VoIP(d) IRC

Accepted Answer

(a) PPP — Point-to-Point Protocol (PPP) is one of the most commonly used data link protocols. It is utilized to establish a direct connection between two nodes and can provide various functionalities such as connection authentication, transmission, encryption, and compression. Communication occurs through a high-speed modem, and PPP is used to connect telephone dial-up lines to the internet.(b) POP3 — Post Office Protocol version 3 (POP3) is a simple and standard method for accessing mailboxes and downloading messages to local computers. Users can receive messages using the POP3 protocol. An advantage of POP3 is that once messages are downloaded, an internet connection is no longer necessary to read the mail, as they are saved on the computer's hard disk.(c) VoIP — Voice over Internet Protocol (VoIP) is utilized for transmitting voice communications. Voice calls undergo digitization, compression, and fragmentation into small packets, which are then transmitted across Internet Protocol (IP) networks. VoIP implementation allows users to carry voice traffic efficiently over an IP network.(d) IRC — Internet Relay Chat (IRC) is an application layer protocol that enables users to share text messages. The sender sends a request to an IRC server, which then forwards the request to another client, facilitating communication between users.

Question 13

Question 14Describe the following networking devices:(a) Routers(b) Bridges(c) Gateways

Accepted Answer

(a) Routers — A router is a networking device that forwards data packets from the source machine to the destination machine over a network using the shortest path available. It can handle different protocols and operates at the network layer, the third layer of the OSI model. Routers utilize IP addresses to connect local area networks to the Internet. In contrast to a hub or a switch, a router possesses advanced capabilities as it can analyze the data being transmitted over a network, make decisions on how it is packaged, and route it to different computer networks.(b) Bridges — A bridge is a device that operates at both the physical layer and the data link layer of the OSI model. It connects multiple network segments (LANs) at the data link layer (Layer 2) of the OSI model. It is a smarter hub as it can filter network traffic on the basis of the MAC addresses.(c) Gateways — A gateway is a network device that connects dissimilar networks. It provides the necessary translation of data received from one network into a format or protocol recognized by devices within another network. A gateway establishes an intelligent connection between a local area network and external networks with completely different structures.

Question 14

Question 15What are Wi-Fi cards? Explain.

Accepted Answer

A WiFi card is either an internal or external Local Area Network adapter with a built-in wireless radio and antenna. It is used in a desktop computer to enable a user to establish an Internet connection. WiFi cards are known as wireless fidelity cards because they allow users to set up connections without any wires.

Question 15

Question 16What is a communication protocol? What is its role in networking?

Accepted Answer

A communication protocol is a formal description of message formats and the rules that two or more machines must follow to exchange those messages.The reason that the Internet works at all is that every computer connected to it uses the same set of rules for communication. The communication protocol used by Internet is TCP/IP.The TCP or Transmission Control Protocol is responsible for dividing the­ file/message into packets on the source computer. It is also responsible for reassembling the received packets at the destination or recipient computer.The IP or Internet Protocol is responsible for handling the address of destination computer so that each packet is routed (sent) to its proper destination.

Question 16

Question 17What is https? How does it work?

Accepted Answer

HTTPS stands for Hypertext Transfer Protocol Secure. It's a protocol that secures communication between two systems, like a browser and a web server, by encrypting data during transmission. When a user accesses a website using HTTPS, a secure connection is established, verifying the server's identity with digital certificates. This encryption and authentication ensure data privacy and integrity, crucial for protecting sensitive information such as passwords and financial data from interception or tampering by malicious entities on the Internet.

Question 17

Question 18What is Ethernet? What is Ethernet Card?

Accepted Answer

Ethernet is a LAN architecture developed by Xerox Corp along with DEC and Intel. It uses either a bus or star topology and supports data transfer rates of up to 10 mbps. Ethernet can connect devices in wired LAN or WAN.An Ethernet card, also known as a network card, network adapter, or NIC (Network Interface Card), is a hardware device that facilitates the connection of nodes within a network. It enables computers to communicate over a computer network. It contains connections for either coaxial or twisted pair cables.

Question 18

Question 19What are hubs? How are active hubs different from passive hubs?

Accepted Answer

A hub is a multi-port and unintelligent network device that simply transfers data from one port of the network to another. It is a hardware device used to connect several computers together using different ports.Active hubs electrically amplify the signal as it passes from one connected device to another. They are often used like repeaters to extend the length of a network. In contrast, passive hubs allow the signal to pass from one computer to another without any alteration or amplification.

Question 19

Question 20What are the facilities provided by the Server in a network environment?

Accepted Answer

Some services provided by a server on a network are:Equipment/Resource Sharing — High quality printers and photocopiers are often designed to connect directly to a network and all authorised users can share the equipment. A server is responsible for such a resource sharing request.Centralised File Saving for Data Sharing — Servers help the user save files to their home directories on the file server, workers can load their documents on any networked computer.Centralised Virus Scanning — Most file servers run virus scanners constantly to detect and take care of viruses introduced by any user on any computer.Centralised Backups — High-capacity tape devices in the file server back up all users' work, usually every night. In case of system failure (or worker failure), lost work can be recovered quickly and easily.

Question 20

Question 21Which communication medium is to be suggested for very effective and fast communication in guided medium?

Accepted Answer

Fiber optic cable is recommended for very effective and fast communication in a guided medium.

Source: This question is from Computer Networks, Computer Science &mdash; Class 12, CBSE Board.
Key Concepts CoveredThis question tests your understanding of the following concepts from the chapter Computer Networks: Question, Communication, Medium, Suggested, Effective, Fast. These are fundamental topics in Computer Science that students are expected to master as part of the CBSE Class 12 curriculum.A thorough understanding of these concepts will help you answer similar questions confidently in your CBSE examinations. These topics are frequently tested in both objective and subjective sections of Computer Science papers. We recommend revising the relevant section of your textbook alongside practising these solved examples to build a strong foundation.
How to Approach This QuestionRead the question carefully and identify what is being asked. Break down complex questions into smaller parts. Use the terminology and concepts discussed in this chapter. Structure your answer logically — begin with a definition or key statement, then provide supporting details. Review your answer to ensure it addresses all parts of the question completely.
Key Points to RememberWrite programs with proper indentation and comments.
Trace through your code with sample inputs to verify correctness.
Explain the logic behind each step of your solution.
Familiarise yourself with common library functions and methods.
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Q10: Question 10 Describe bus topology and star topology.
Q11: Question 11 Define the following terms: (a) Baud (b) Communication channel (c) Hub (d) Repeater
Q12: Question 12 What is modem? Define the functioning of internal modem and external modem.
Q13: Question 13 Expand and explain the following terms: (a) PPP (b) POP3 (c) VoIP (d) IRC
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