Digital Book Class-10 2nd edition

Smart Computer Science Book-10 Approved by Curriculum Development Center (CDC) 1

Approved by Curriculum Development Centre (CDC), Santothimi Bhaktapaur Smart Computer Science Book-10 Author Prabhu Ram Khadka M. Sc. IT (SMU), B. Ed. (TU) Memorica Pvt. Ltd. Publisher & Distributor Maitidevi, Kathmandu 2 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Book : Smart Computer Science Book-10 Author : Prabhu Ram Khadka Language Editor : Keshav Nepal Publisher : Memorica Pvt. Ltd. Maitidevi, Kathmandu Ph: 01-4438703/ 9813303490/9841816625 Edition : 1st 2079 B.S. (2022 AD) 2nd 2080 B.S.(2023 AD) Copyright : All rights reserved with the author For suggestion and advice, please contact at [email protected] Cell : 9841816625, 9813303490 (Viber/Messenger) https://www.facebook.com/memorica.prakashan URL: www.memoricaITC.com Approved by Curriculum Development Center (CDC) 3

SEE Practical Evaluation Pattern Pg. no. 1 - 39 TABLE OF CONTENTS 40 - 55 56 - 77 Ch. Title 78 - 106 1. Network & Telecommunication 107 - 122 2. Internet & Services 123- 142 3. Ethical & Social Issues in ICT 143 - 158 4. Computer Security 159 - 166 5. Digital Commerce 167 - 190 6. Contemporary Technology 191 - 199 7. Number System 200 - 212 8. Database Management System 213 - 228 9. Creating Database with Access 229 - 240 10. Entering & Editing Data 241 - 278 11. Queries in MS-Access 279 - 297 12. Creating Forms & Report 298 - 332 13. Review QBASIC Programming 333 - 334 14. Modular Programming 335 - 336 15. File handling in Q-BASIC 337 - 338 16. Basic of C Programming 339 - 346 347 -347 Project Work 348-348 Abbreviation SEE Theory Question Pattern SEE Theory Model Question SEE Practical Evaluation Pattern SEE External Practical Model Question 4 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 N & Tetwork elecommunication CHAPTER 1Chapter Includes • Introduction to Communication • Introduction to Telecommunication and Data Communication • Mode of Transmission and Transmission Signal • Communication Media • Wireless Communication Technology • Introduction to Computer Network • Components of Network • Network Categories • Network Topologies INTRODUCTION TO COMMUNICATION Communication refers to the exchange of information between two or more parties with the use of common signals, symbols, or behaviors. There are various methods of communication such as face-to-face conversation, telephone calls, newspapers, bulletins, e-mails, television programs, etc. The word ‘communication’ is derived from the Latin word ‘commūnicāre’ which means to share. Fundamentally, communication involves three parts: a sender, a message, and a receiver. It is a continuous and dynamic process involving more than one party. It includes verbal, non-verbal, and electronic means of interaction. Broadly speaking, communication can be defined as the process of meaningful interaction among two or more entities. The ability to communicate effectively is one of the most important life skills in the learning process. People have been communicating since the start of civilization. Besides face-to- face conversation, there are other methods of communication. For eg: In ancient times, a ruler of a clan used 'a messenger' to communicate with the rulers of other clans. In Hindu mythology, Narad Muni is the messenger for the gods. Similarly, in the Hindu epic Ramayan, Lord Ram’s messenger was Lord Hanuman. Also, Approved by Curriculum Development Center (CDC) 5

Network & Telecommunication folklores, where birds are used as messenger for effective communication over long distances, is still widespread publicly trusted in our societies. In present times, communication has advanced leaps and bounds because of new developments in science and technology. Various sophisticated devices which aid for fast and reliable communication are available at our disposal. The revolutionary invention in the field of communication was the telephone invented in 1876 AD by Alexander Graham Bell. It changed how people perceived communication in the 19th century. Sequentially, the development and advancement of microcomputers in the 20th and 21st centuries gave a newer definition to communication as we realize it today. Efficient communication has transformed the once vast world into a global village today. TELECOMMUNICATION Telecommunication, or Telecom, is the transmission of signals over long distances through suitable media. It allows people to quickly communicate with others across the street, city, or the globe. There are many means of telecommunication such as mobile networks, radio broadcasts, computer networks, internet, etc. Therefore, watching TV programs, sending e-mails, talking over the phone, or sending a fax is possible. So, we must thanks to telecommunication. The beginning of Telecommunication can be traced back to the invention of the telegraph in 1837 AD, followed by the telephone in 1876 AD. Radio waves were identified by the German physicist Heinrich Hertz in the late 1800s, and television broadcasts started in the early 1900s. Today, popular forms of telecommunication include, but are not limited to, the internet, phone networks, and radio broadcasts. At its structural level, telecommunication uses two types of data transmission signals; analog and digital. The identifying characteristic between these two signals is that an analog signal uses a continuous signal which represents physical measurements, whereas digital signals are discrete-time signals generated by digital modulation. An example of the analog signal is the human voice in the air, whereas an example for the digital signal is a computer hard disk. 6 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 DATA COMMUNICATION Data communication is a subset of telecommunication that involves the to-and-fro of data from computers and components of the computer system. It is the process of transmission of information between two or more points using either analog or digital signals. Some examples of data communication are sending e-mails, fund transfers from a bank to another, video conferences, sharing of documents through local networks and the internet, uploading a website on the internet, etc. Ways of Communication There are two ways of communication. They are as follows: i) One-way communication: For example:- radio, television, newspaper, etc. ii) Two-way communication: For example:- online-chat, telephone call, video conference, etc. Elements of Data Communication Data communication is a system that comprises different elements to communicate such as hardware and software. Fundamentally, five elements are required to form a data communication system. They are as follows: Data : Data is the primary element that is to be transmitted or communicated. Sender : A sender is a hardware device that is used to send data. It is also known as a source or transmitter. Medium : Medium is the path through which data travel during transmission. It is also called the information superhighway. Receiver : A receiver is a hardware device that receives data and information sent by the sender. Protocol : It is a software or set of rules that are to be followed by the sender and receiver to communicate. MODE OF DATA TRANSMISSION Data transmission on a communication channel between two machines can take place in several ways. Here, we discuss the three main ways or modes of data transmission. They are as follows: a. Simplex Mode b. Half-duplex Mode c. Full-duplex Mode Simplex Mode In the simplex mode of data transmission, data flow is unidirectional; i.e. data Approved by Curriculum Development Center (CDC) 7

Network & Telecommunication flows from the sending device to the receiving device. A simplex connection is often desirable where the data need not flow in both directions. In simpler terms, it can be compared to a one- way road. For example, the computer can send a message to the printer, but the printer need not send any data or message to the computer. Other examples of the simplex mode of data transmission are radio and television broadcasts. Half-duplex mode Half-duplex mode is also known as an alternating connection or a semi-duplex mode of data transmission. Here, data transmission is bi- directional but not simultaneous. So, it means a half-duplex system can alternatively send and receive data. It can be visualized as a single-lane bridge where vehicles on one side must wait until traffic incoming from the opposite side has crossed the bridge. Some of the popular examples of the half-duplex mode of communication are wireless communication systems such as walkie-talkies, web browsing, etc. Full-Duplex Mode In the full-duplex mode of data transmission, data can be transmitted in both directions simultaneously. This bi-directional system allows both communicating devices to send and receive data simultaneously. A full-duplex connection can be thought of as a two-lanes bridge, where vehicles can simultaneously travel in both directions in their respective lane. A real-world example of the full-duplex mode of transmission is the telephone system where both the caller and the receiver can talk at the same time. TRANSMISSION SIGNAL A transmission signal is an electrical signal generated from the original information that is to be transmitted, using a transducer. This is also known as the baseband signal. Transmission is the process of sending and propagating analog or digital signal using a transmission medium such as wired, optical, or wireless 8 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 electromagnetic. When talking about devices around us, computers produce digital signals whereas telephones produce analog signals. So, it can be said that essentially there are two types of signals: i) Analog Signal and ii) Digital Signal Analog signal Analog signals are the signals in which the voltage and the current vary continuously with time. For example; voltage, sound, music, the sound produced by a tuning fork, etc. The signals can be represented by sine waves and are sent in continuous waves during data transfer. For example, in the case of an earthquake, a seismometer will provide recordings of a range of consecutive measurements. Digital Signal In a digital signal, the voltage and current vary with time in the form of a pulse which is discontinuous in nature. Signals are denoted by square waves. The digital signal has only two values, high and low which is represented in binary format as 0 and 1. For example; output of a computer is a digital signal. Digital signal’s bandwidth is high, and can only take a finite number of possible values. For example, Morse code is based on two discrete values, a dash, and a dot. Letters, numerals, and punctuation are all represented by different combinations of these two values. As a result, a Morse code message will result in a collection of digital data. Bandwidth Bandwidth is the maximum amount of data transmitted over the internet within a specified time. It is also referred to as the transmission capacity of a connection, which is one of the primary factors when determining the efficiency and speed of a network or the internet connection. Generally, it is measured in ‘bits per second’ bps. Metaphorically, bandwidth is similar to a water pipeline; the wider the pipe, the greater volume of water that can flow through it. The same principle applies to bandwidth strength and the flow of volume of data. COMMUNICATION MEDIA 'Communication media' as a term is also known as transmission media or transmission channel. It can be defined as the media or means of communication through which communication is established. In simple terms, it is a pathway Approved by Curriculum Development Center (CDC) 9

Network & Telecommunication that carries information from the sender to the receiver in which various types of cables or waves are used to transmit data. Generally, data are transmitted through electrical or electromagnetic signals. An electrical signal is a form of current which is transmitted through copper wires and optical fibers. An electromagnetic signal is the series of electromagnetic energy pulses at various frequencies. It is transmitted through atmosphere, and vacuum. Factors like bandwidth, cost, the comfort of installation, delay and maintenance vary according to the selected media. There are two types of communication media. They are as follows: a. Wired or Guided Media or Bounded Transmission Media b. Wireless or Unguided Media or Unbound Transmission Media Wired or Guided Media Guided media is defined as the physical medium through which the signals are transmitted. It is also known as Bounded media. Twisted pair cable, coaxial cable, and fiber optic cable are common bound transmission mediums. Each has its own features, such as transmission speed, noise effect, physical look, cost, and so on. The following are the types of wired or guided media: i) Twisted Pair ii) Coaxial cable iii) Fiber optic Twisted Pair Twisted pair cable is a guided media. It is popularly used to connect devices over a short distance to transmit the signals. Two plastic-insulated copper wires are twisted together to produce a single medium in a twisted pair cable. Only one of these two wires transmits the real signal, while the other serves as a ground reference. Noise (electro-magnetic interference) and crosstalk can be reduced by twisting wires together. Twisted pair cables are mainly divided into two types. They are as follows: i) Shielded Twisted Pair (STP) Cable ii) Unshielded Twisted Pair (UTP) Cable Shielded Twisted Pair: STP cables have a metal-foil-covered twisted wire pair as a result it provides better protection against EMI(Electromagnetic Interference) than UTP like noise and crosstalk. This type of cable is mainly used for industrial purpose not so much in home or business. Its bandwidth is 10 to 500 Mbps (Megabits per second). RJ 45 connector is used in STP. Unshielded Twisted Pair (UTP) Cable: UTP cables come with several twisted-pair 10 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 cables surrounded by an outer jack with no metallic shield. It is popularly used for data as well as voice transmission. Due to its thin diameter without a shield, it is very easy to install. It comes in different categories; CAT-1 to CAT- 7. The bandwidth of the cable depends upon the category. CAT-1 and CAT-2 are used for telephone communication whereas CAT-3 to CAT-6 are used in computer networks for data communication. RJ-45 (Resister Jack-45) connector is used for CAT-5 and CAT-6. Though STP cables have a better noise rejection capacity than UTP, UTP can cover distances up to 100 meters. UTP has low bandwidth than STP having standard data signal transferring rate is 100 Mbps. Differences between STP and UTP UTP STP 1. It is an unshielded twisted pair. 1. It is a shielded twisted pair. 2. UTP cable is a twisted pair cable with wires 2. It is enclosed within a foil or mesh shield that are twisted together. 3. It is cheaper than STP cables. 3. It is more expensive than UTP cables. 4. It is used for short distance. 4. It is used for long distance. 5. Crosstalk is more than STP cables. 5. Crosstalk is less in STP cables than UTP cables. 6. UTP cables are noisier. 6. STP cables are less noisy. 7. Transferring speed of the data signal is slow 7. Transferring speed of the data signal is high Coaxial cable braided shield foil shield center connector Coaxial cable is a two-conductor cable in which one conductor forms an electromagnetic shield around the other. The two conductors are separated by insulation. It is a constant electric resistance transmission cable dielectric and it has better noise rejection outer jacket power. This sort of media is used in baseband and broadband transmissions, long-distance telephone lines, computer network connections, and distributing cable television signals. It has a high bandwidth as well as noise immunity power. Coaxial cables do not produce external electric and magnetic fields and are not affected by them. Although it is expensive and it makes them ideal for transmitting signals. BNC (Bayonet Neill–Concelman) or ‘T’ connecter is used with this cable. Approved by Curriculum Development Center (CDC) 11

Network & Telecommunication Fiber optic Fiber-optic cable is the most widely used cable nowadays. It consists of a number of optical fibers which are bundled together, and are covered with less refractive indexed cladding to avoid light leakage to the surroundings. The core of fiber optic cable is made of high-quality glass or plastic. Data are transferred in the form of light along the fiber-optic cable at the speed of light. Its bits per second data transmission rate is in billions. The data error is minimal and more powerful in a fiber-optic cable. There are many types of fiber optic cable connectors: SMA (Screw Mounted Adapter), STC (Straight Tip Connector), FC (Ferrule Connector), LC (Lucent Connector), MT-RJ (Media Termination- Recommended Jack) Connectors, MUC (Miniature Unit Connectors), SC (Subscriber Connectors), etc. Wireless or Unguided Media or Unbound Transmission Media: Wireless or unguided media transmit electromagnetic waves without the help of any medium. In unguided media, wireless signals are spread through the air and received and interpreted by appropriate antennas. When an antenna is connected to a computer's or wireless device's electrical circuit, it transforms digital data into wireless signals that are broadcast throughout the frequency range. These signals are received by the receptor, which transforms them back to digital data. Nowadays, wireless communication is becoming more and more popular and wireless LANs are being installed in schools, colleges, and offices. This type of transmission uses microwaves, radio waves, infrared waves, and satellite communication. Microwave Microwave is a line-of-sight wireless communication process that utilizes high-frequency radio waves to transmit and receive audio, video, data, and information. Obstacles such as hills, mountains, and buildings can block the signals. Since the typical line of sight due to the Earth’s curvature is only 50 km to the horizon, repeater stations must be placed so that data signals can bounce, skip and jump across a large geographical area. Microwaves operate at high operating frequencies of 300 MHz (1 m) to 300 GHz (1mm). Microwaves are 12 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 widely used in modern technology, such as mobile phones, fixed telephones, wireless networks, etc. Radio Wave Radio wave refers to a type of electromagnetic wave that is used to transmit data across long distances over the air. Radio waves are easy to generate. Sometimes radio waves are also referred to as radio frequency (RF) signals. Its frequency can range from as low as 30 hertz to as high as 300 gigahertz. Due to its large wavelength, radio waves can pass through some solid structures like walls. There are two major types of radio waves, they are as follows: i) Baseband ii) Broadband Lower-frequency radio waves can pass through walls, but higher-frequency radio waves travel in a straight path and bounce back. Low-frequency waves lose power as they travel long distances. Hence, the power of high-frequency radio waves is greater. Radio waves are used in standard broadcast radio and television, shortwave radio, cellular telephony, satellite communication, broadcasting, radar and navigation systems, etc. Infrared waves Infrared waves are the types of electromagnetic waves having a frequency range between 300 GHz to 400 GHz. These waves are unable to travel across long distances. Hence, they are used for short-range communication and propagate along a line of sight. Because of their high frequency, these waves are unable to travel through solid things such as walls. The most frequent usage of infrared waves is in remote controls for televisions, DVD players, and audio systems. Differences between Guided Media and Unguided media Guided Media Unguided media 1. The signal is transmitted through a 1. The signal is broadcasted through the air. physical path or conductor. 2. It is useful for point-to-point connections. 2. It is useful for broadcasting purposes. 3. Signals are transmitted in the form of 3. Signals are transmitted in the form of electromagnetic voltage, current, or electronic pulses.. waves. 4. Provides direction to the signal. 4. Does not direct the signal. 4. Examples: twisted pair cable, coaxial 4. Examples: microwaves, radio waves, and infrared cable, and fiber-optic cable. waves. Approved by Curriculum Development Center (CDC) 13

Network & Telecommunication WIRELESS COMMUNICATION TECHNOLOGY The term wireless communication was introduced in the 19th century. Over the subsequent years, wireless communication technology has developed rapidly. It is one of the most popular mediums of transmission of information from a device to another. In this technology, information is transmitted through the air with the help of electromagnetic waves like IR (Infrared), RF (Radio Frequency), satellites, etc. Therefore, wireless communication technology omits the use of cables, wires, or other electric conductors. Some of the most popular wireless communication technologies are WiFi, microwave communication, infrared communication, Bluetooth, etc. Satellite Communication Satellite communication is a type of wireless communication technology which enables people in every corner of the world to stay connected. When the signal (a beam of modulated microwave) is sent near the satellite, then, the satellite amplifies the signal and sends it back to the antenna receiver which is located on the surface of the earth. Satellite communication contains two main components: the space segment, and the ground segment. The ground segment consists of fixed or mobile transmission, reception, and additional accessory equipment whereas the space segment is the satellite itself. Satellites are used primarily for communications in orbit around the Earth. The geostationary orbit, which is 36,000 kilometers above the Earth's Equator, is most known for its many satellites, which are used for a variety of telecommunications, including telephone, radio, television, internet, and military applications. The signals from these satellites are transmitted all over the globe. With the help of satellite communication, we can share information through the internet, fax, telephone, etc. globally. Hence, it is one of the cheapest, effective and fastest mediums to share data and information. Laser Communication System The laser communication system is another wireless mode of telecommunica­tion. Laser communication came into existence in 1960 AD. In this mode of communication, the information is transferred through free 14 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 space. Here, the signals are transmitted from the wireless transmitter to a wireless receiver without any interruption or blockage. The carrier used for the transmission signal is typically generated by a laser diode. Two parallel beams are needed, one for transmission and another for the reception. It is less expensive because it doesn’t use wires and cables. One thing to be careful about while using the laser mode of communication is that the signals must flow without any obstruction. Bluetooth Technology Bluetooth is a short-range wireless communication technology that allows devices such as mobile phones, computers, and peripherals to transmit data or voice wirelessly over a short distance. The purpose of Bluetooth is to replace the cables that normally connect devices. Popularly, it is used to establish the connection and share information. It covers a maximum distance of 10 meters, and cannot resist disturbances such as walls. Wi-Fi (Wireless Fidelity) Wi-Fi is a low-power wireless communication technology that is used by various electronic devices such as smartphones, laptops, tablets, etc. In the Wi-Fi system, a router works as a communication hub wirelessly. Hence, these networks allow users to connect only within close proximity to the router. Wi-Fi is very common in networking, as it affords portability wirelessly. From a security viewpoint, Wi-Fi networks need to be protected with passwords, otherwise, it can be accessed by anybody. INTRODUCTION TO COMPUTER NETWORK A computer network is a connection of two or more computers or devices in order to share resources such as printers and storage devices, computer programs, files, or electronic communication signals. The computers on a computer network may be linked through cables, telephone lines, radio waves, satellites or infrared Approved by Curriculum Development Center (CDC) 15

Network & Telecommunication light beams. Advantages of Computer Network a. Files can be shared over the network. b. Resources such as printers and storage devices can be shared over the network. c. Great storage capacity. d. Computer networks are cost-efficient, e. Computer networks help in facilitating communication. f. Computer networks can be more secure when a reliable authentication method is implemented. Disadvantages of Computer Network a. Failure of server stops applications from being available in the network. b. Network failure may cause loss of data. c. User’s work depends upon a network. d. Sometimes a system may be hacked. e. Computer virus can spread through computer network. COMPONENTS OF NETWORK The computer network is a system that includes various components to perform the task. Fundamentally, two types of components are included in the network. They are: i) Hardware components ii) Software components Hardware Components Physical components and devices that are used to connect the computers with the network are called hardware components. Some basic hardware components are as follows: Server Computer A network server is a computer designed to process, request, and deliver data to other (client) computers over a network. Network servers are configured with additional processing, memory, and storage capacity to handle the load of servicing clients. Network operating system software is stored on this computer. Common types of network servers include web server, proxy server, FTP(File Transfer Protocol) server, online game server, 16 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 client/server, etc. Client computer/Work station Clients are computers or devices which access and use the network as well as share network resources. They are also users of the network, as they can send and receive requests to/from the server. Therefore, these are also called workstations. Workstation is also used to run the user's application. It is less powerful than a server computer and has less processing speed and storage capacity. Hub A hub is a hardware device that shares the network connection between multiple devices. When a computer requests some information from a network, it first sends the request to the hub through a cable. Then, the hub will broadcast this request to the entire network. All the devices will check whether the request belongs to them or not. If not, the request will be dropped. Since they do not have the intelligence to find out the best path for data packets, it leads to inefficiencies and wastage. No security concerns, creating unnecessary traffic, consuming more bandwidth and a limited amount of communication are drawbacks of the hub. In the present day, the use of hub is outdated, and it is replaced by more advanced computer network devices such as switches and routers. Switch Aswitch is a hardware device that connects multiple devices on a computer network. It contains more advanced features than a hub and contains an updated table that specifies the physical address to transmit the data signal. A switch delivers the message to the correct destination based on the physical address present in the incoming message. Such address is called MAC (Media Access Control) address. Approved by Curriculum Development Center (CDC) 17

Network & Telecommunication Therefore, we can say that a switch provides a direct connection between the source and destination. It also increases the speed of the network. Hence, proving it to be more intelligent than a hub. Difference Between Hub and Switch Hub Switch A hub is operated on the physical layer of the OSI The switch is operated on the data link layer of model network layer. the OSI model network layer. A hub uses a half-duplex mode of transmission. A switch uses a full-duplex mode of transmission. A hub is not an intelligent device. A switch is quite intelligent when compared to a hub. A hub is a simple and old device that is not of A switch is a sophisticated device that is used popular use. very popularly. A hub is a broadcast type of transmission. A switch is a unicast, multicast and broadcast type of transmission. A hub does not store any MAC address and IP A switch store MAC address to transfer the data. address to transfer the data. Router A router is a network layer hardware device that transmits data from one LAN to another if both networks support the same set of protocols. It also amplifies the signal before transmitting them, hence it is also called a repeater. A router is used to receive, analyze and forward the incoming packets to another network. A router works in the third layer (Network layer) of the OSI (Open Systems Interconnection) reference model. It can help connect with multiple dissimilar networks having the same protocol. It filters and forwards information among different networks based on IP (Internet Protocol) address. It also forwards the packet based information available in the routing table. It also determines the best path from the available paths for the transmission of the packet. So, it is called an intelligent device and gateway of data transmission. 18 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Differences Between Router and Switch Router Switch A router works in the network layer of the OSI A switch works in the data link layer of the OSI model network layer. model network layer. A router can be used by LAN, MAN, and WAN. A switch is used by LAN only. A router falls into the category of an intelligent A switch falls into the category of a semi- device. intelligent device. The main objective of a router is to connect The main objective of the switch is to connect various networks simultaneously. various devices simultaneously. Through a router, the data are sent in the form Through a switch, the data are sent in the form of packets. of a packet and frame. Gateway The gateway is the network node that connects two different networks using different protocols. Gateways are also called protocol converters and can operate at any network layer. It also acts as a 'gate' between two networks. They work as messenger agents that take data from one system, interpret it, and transfer it to another system. It may be a router, switch, firewall, server, or other devices that enable traffic to flow in and out of the network. Repeater Repeaters are network devices operating at the physical layer of the OSI (Open Systems Interconnection) model that amplifies or regenerates an incoming signal before retransmitting it. They are incorporated into networks to expand their coverage area. They are also known as signal boosters or signal extenders. Approved by Curriculum Development Center (CDC) 19

Network & Telecommunication Cable The cable is also known as a data cable. It is commonly called Ethernet cable. It is used to connect a device to transmit data from one computer to another in the network. The most commonly used cables are coaxial cables, twisted pair cables and optical-fiber cables. NIC (Network Interface Card) A network interface card (NIC) is a hardware component, typically a circuit board or chip, which is installed on a computer so that it can connect to a network. NIC is also referred to as an Ethernet card and a network adapter. The network interface card sends, receives, and controls data flow between the computer and the network. Network cards can communicate with each other over the same network using a network switch, or if two computers are directly connected. When computers need to connect to a different network (e.g. internet), they must use a router to route network packets to the correct network. Connectors The connectors are the interface between NIC of computer and cable which passes the data from one computer to another. There are different types of connectors based on the cable which are shown in the following table: Connectors Cable BNC (Bayonet Neill–Concelman) T connector Used with Coaxial Cable RJ45 (Registered Jack 45) Used with UTP Cable ST (Straight-Tip Connector) Used with Fiber Optic Cable SC (Subscriber Connector) FC (Ferrule Connector or Fiber Channel) 20 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Modem Modem stands for modulation and demodulation. Modem is a device that converts digital signal into analog and analog signal into digital. The process of converting digital signal into analog signal is called modulation. The process of Internal and external modem. converting analog signal into digital signal is called demodulation. Modem sends and receives data through telephone lines or TV cable in the form of analog signal but computer receives and stores data in digital form. So, the modulation and demodulation processes are most essential to convert digital data to analog and vice versa. The sending and receiving computers both must have modems. Basically two types of (internal and external) modems are available. Internal modems are circuit board that plugs into one of the expansion slots on the motherboard. An external modem is kept outside the computer. It is connected to the computer through a serial or USB (Universal Serial Bus) port. Software Component of Network 21 Software is the major component of the network which helps to establish the network logically to share data and other resources. The following are the software components that are used in the network: Network Operating System Software (NOSS) Network operating system software is a broad range of software used for designing, implementing, operating, and monitoring computer networks. Novel Netware, Windows Server, and Linux are some of the popular network operating system software. NOSS is stored in the server computer. Approved by Curriculum Development Center (CDC)

Network & Telecommunication Device Driver A device driver or hardware driver is a group of files that enable one or more hardware devices to communicate with the computer's operating system. Without drivers, the computer is unable to send and receive data correctly to hardware devices, such as a printer, modem, network card, etc. Communication Protocol A protocol is a set of rules and guidelines for sending and receiving information among computers and other electronic devices in the network. Rules are defined for each step and process which must be followed by the connecting devices in the network to successfully transmit data. These rules include what type of data may be transmitted, what commands are used to send and receive data, and how data transfers are confirmed. Some of the common protocols used in the computer network are as follows: TCP : Transmission control protocol is used for communication over a network. In TCP, the data are broken down into small packets and then sent to the destination. TCP works in conjunction with IP to make sure that the packets are transmitted to the right address. Internet Protocol (IP) : IP is also working with TCP. It is an addressing protocol. IP addresses packets route them and show different nodes and network unless it reaches its right destination. The IP protocol is developed in 1970. FTP : File transfer protocol is a standard protocol used for transferring files from a host to another. It is mostly used to transfer web page files from their creator to a computer that serves other computers on the internet as a server. SMTP : Simple Mail Transfer Protocol is used by mail servers to send, receive, and/or relay outgoing mail between email senders and receivers. HTTP : HTTP (Hypertext Transfer Protocol) is based on the client and server model. It is used to make a connection between the web client and the webserver. HTTP shows the information on web pages. Ethernet : Ethernet protocol is a standard LAN technology. It transmits the data in digital packets. If any computer wants to use this protocol, it should contain Ethernet Network Interface Card (NIC). The card is implemented with a unique address code fixed in the microchip. Telnet : Telnet is an application protocol. It is used on the Internet or local area network to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. It is commonly used for the remote login process. If a command is given on a local computer, it is executed on a remote computer. Telnet is also based on the client and server model. 22 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Gopher : Gopher is an application layer protocol, which is used for searching and retrieving documents on remote webservers. In present days, Gopher has been succeeded by HTTP, hence it has limited implementations. ARP : The role of Address Resolution Protocol is to convert a network address of a computer to MAC address. POP : Post Office Protocol is an application-layer internet standard protocol used by e-mail clients to retrieve e-mail from a mail server. PPP : Point-to-Point Protocol is a communication protocol of the data link layer that is used to transmit multiprotocol data between two directly connected (point-to-point) computers. It can provide connection authentication, transmission encryption, and compression. CDP : Cisco Discovery Protocol is a proprietary data link layer protocol developed by Cisco, a networking hardware company, to share information in connected Cisco devices. VoIP : Voice over Internet Protocol (VoIP), also called IP telephony, is a technology that facilitates making voice calls using a broadband Internet connection instead of a regular or analog phone line. IPX/SPX : Internet Packet Exchange/Sequential Packet Exchange, IPX/SPX is a network layer protocol developed by Novell. It exchanges information between network clients, applications, and network peripherals. Net BEUI : NetBIOS Extended User Interface is a networking protocol developed by IBM and Microsoft in 1985. It is used in work group-size local area networks. DHCP: Dynamic Host Configuration Protocol is a network management protocol used to assign an IP address and other network configuration parameters to each device on a network so they can communicate with other IP networks. DNS : Domain Network System (DNS) protocol helps internet users and network devices discover websites using human-readable hostnames, instead of numeric IP addresses. NETWORK CATEGORIES There are various types of computer networks available. We can categorize them according to their size as well as their purpose. The size of a network is expressed on the basis of geographic area and number of computers. It includes devices placed in a single room to millions of devices spread across the world. Some of the most popular network types are: i) LAN (Local Area Network) ii) MAN (Metropolitan Area Network) iii) WAN (Wide Area Network) Approved by Curriculum Development Center (CDC) 23

Network & Telecommunication LAN (Local Area Network) LAN (Local Area Network) is a group of computers and peripheral devices which are connected in a limited area of 100 meters to 1000 meters. It is commonly used in networks of a school, laboratory, home, and office buildings. It is a widely used network for sharing resources like files, printers, games, and other applications. The simplest type of LAN network is to connect computers and a printer in someone's home or office. In general, LAN is connected through a communication medium such as twisted-pair cables and coaxial cables. Characteristics of LAN • It covers a small area i.e. 100 meters to 1000 meters. • The data are transferred at an extremely fast speed in LAN. • It is less costly as it is built with inexpensive hardware components such as hubs, network adapters, and ethernet cables. • Being a private network, it is never controlled by an outside regulatory body. MAN (Metropolitan Area Network) A metropolitan area network (MAN) is a computer network that connects computers within a metropolitan area, which can be a single large city, multiple cities and towns, or any given large area with multiple buildings or a small region of 5 kilometers to 50 kilometers in diameter. A MAN is larger than a local area network (LAN) but smaller than a wide area network (WAN). Speeds of MAN ranges in terms of Mbps (Megabits per second). Devices used for transmission of data through MAN are modem and wire/cable. Some examples of MAN are telephone company networks that can provide a high-speed DSL (Digital Subscriber Line) to the customer and the cable TV network in a city. 24 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Characteristics of MAN • It generally covers towns and cities ranging from 5 kilometers to 50 kilometers in diameter. • The data transmission speed is moderate. • Communication mediums used for MAN are optical fibers, cables, etc. • Ownership can be either private or public. • It is hard to design and maintain a MAN as it needs more cables in joining connections from one place to another. Wide Area Network As the name suggests, Wide Kathmandu Biratnagar Area Network (WAN) covers a wide area that may span local provinces or international Office1 borders. It spans over a large geographical area through Office1 telephone lines, fiber optic cables, or satellite links. Office2 Office2 Telecommunication networks, banking networks of a country, and ISP (Internet Service Provider) networks are good examples of WAN. The internet is one of the biggest WANs in the world. WAN may use advanced technologies such as Asynchronous Transfer Mode (ATM), Frame Relay, and Synchronous Optical Network (SONET). Characteristics of MAN • It generally covers large distances over states, countries, and even continents. • Its data transmission speed fluctuates from very slow to very fast. • Communication mediums used are satellites and PSTNs (Public Switched Telephone Networks). • WAN may be managed by multiple administrations. • It is widely used in the field of business, government, and education. NETWORK ARCHITECTURE Network architecture is a design in which all computers on a computer network are organized. It includes the physical and logical design of the software, hardware, protocols, and media for the transmission of data. An architecture defines how the computers should get connected to get the maximum advantages of a computer network such as better response, time, security, flexibility, etc. The three most popular computer network architectures are centralized computing network, client-server architecture, and P2P (Peer to Peer) architecture. Approved by Curriculum Development Center (CDC) 25

Network & Telecommunication Centralized Computing Network In this network architecture, one is the server computer which is also known as the host computer. All or most of the processing/computing task is performed on this host computer. It is responsible for delivering application logic, processing, and providing computing resources to the attached client computers. These client computers are connected to the host computer just for input/ output operation, they don't have any processing capabilities. Linux or UNIX operating system is used in centralized network architecture. Advantages of Centralized Computing Network • It helps in reducing the cost because it does not utilize a great deal of hardware and machines. • It provides better data security. • Processing task is consistent. • The data and programs on each information system are independent of other information systems. Disadvantages of Centralized Computing Network • Large data storage is required in the host computer. • There is a possibility of abrupt failure of the entire system. • The ability to respond to requests might be delayed. • It is difficult to maintain the server because there is only one server node. • If the server node fails and there is no backup, the data are lost. Client Server Architecture In client server architecture, a central computer acts as a hub and serves. All the shared data are stored on the server computer which are shared with the client computer when a request is made by the client computer. All the communication takes place through the server computer, for example, if a client computer wants to share the data with the other client computer, then it has to send the data to the server first and then the server will send the data to another client. 26 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 In this architecture, users are assigned rights, so users need to log in to the server to access resurfaces of the network according to the rights provided by the administrator. The network administrator is there having full rights of the entire network. He is responsible to keep and manage the record of the users and their rights as well as data security and other resources management of the network. Advantages of Client Server Architecture • Data backup is easy and cost effective as there is no need to manage the backup on each computer. • Performance is better as the response time that greatly improves because the server is more powerful computer than the other computers in the network. • Security is better as unauthorized access are denied by server computer and all the data goes through the server. • Flexibility is not an issue in this architecture as a large number of computers can be connected with server. Disadvantages of Client Server Architecture • In case of server failure, none of the clients’ requests can be fulfilled, the entire network will be down. • The server maintenance cost is high as the server is the main component in this architecture. • In a situation where all the clients simultaneously request data from the server, it may get overloaded, consequently leading to traffic in the network. • The cost is high as the server needs more resources to handle that many client requests and to be able to hold large amounts of data. Peer to Peer Architecture In peer-to-peer (P2P) networking, a group of computers are linked together for processing data with equal permission and responsibility. Every computer in the network uses the same resources as other computers. All the connected computers function as servers and workstations to share data, information, and other resources of the network. There is no central computer that acts as a server, rather all the computers act as a server for the data stored in them. This architecture is suitable for small offices and homes, where data and other securities are not required. Approved by Curriculum Development Center (CDC) 27

Network & Telecommunication Advantages of a Peer to Peer Architecture • It is less costly as there is no central server that has to take the backup. • In case of a computer failure, all other computers in the network are not affected and they will continue to work as same as before the failure. • Installation of peer-to-peer architecture is quite easy as each computer manages itself. Disadvantages of a Peer to Peer Architecture • Each computer has to take the backup rather than a central computer and the security measures are to be taken by all the computers separately. • Flexibility is an issue in a peer-to-peer architecture as connecting each computer to every computer is a headache on a very large network. • Its security and performance are poor. • Required software needs to be installed on every computer. NETWORK TOPOLOGIES Network topology refers to the physical or logical layout or model of a network. It defines the placement of different nodes and connection patterns with each other. Alternatively, the network topology may describe how the data are transferred between these nodes. There are two types of network topologies: physical and logical. Physical topology emphasizes the physical layout of the connected devices and nodes, while logical topology focuses on the pattern of data transfer between network nodes. However, both physical and network topologies can be categorized into many models, but here, we discuss three basic models: Bus Topology The bus topology is designed in such a way that all the stations are connected through a single cable known as the backbone cable. This backbone cable is considered as a \"single lane\" through which the message is broadcast to all the stations. All the nodes (stations) are connected to this backbone cable through drop line. There is a device called tap (T connector) that connects the drop line to the backbone cable. The terminators are attached at both ends of the backbone cable. Any computer can be made server computer in this topology. When any station sends data, the data are broken down into small part called packet or datagram which is transmitted in both directions through the bus. As the message passes each station, the station checks the message's address. If the address of the messages matches the station's address, the station receives 28 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 the message. If the address is not matched, the bus carries the message to the next station, and so on. If the backbone cable is open, the data signal comes back which is known as the signal reflection. Advantages of bus topology • Connecting a computer or peripheral to a linear bus is easy. • This topology requires the least amount of cabling to connect the computers, therefore, it is less expensive. • It is easy to extend the bus since two cables can be joined into one long cable with a connector. Disadvantages of bus topology • The entire network shuts down if there is a failure in the backbone cable. • It is difficult to detect faults. • This network topology is very slow as compared to other topologies. Star Topology In the star topology, all the computers and networking devices are connected to a single hub using a point-to-point connection. This single hub acts as the central hub for all the computers. Data always transmit through the central hub that means when a sender sends data, it will flow through the central hub and go to the receiver. The central hub in star topology acts as a repeater. If any one of the nodes fails, it does not affect another node because each node is connected individually with the hub. Twisted pair, coaxial cable and fiber optic can be used as a transmission medium in this technology. The whole network depends upon a single hub. The central hub may be a router, switch, or hub. Advantages of star topology • Star topology is easy to install. • It does not affect other nodes if any one of the nodes fails. • Fault detection and removal of faulty components are easier in a star topology. Disadvantages of star topology • It needs more cable in comparison to the bus topology, making it more costly. • If the hub fails, the attached nodes are disabled. • The cost of the hub makes the network expensive when compared to bus and ring topology. Approved by Curriculum Development Center (CDC) 29

Network & Telecommunication Ring Topology In the ring topology, all the computers and networking devices are connected in a circular path or a closed loop. In this topology, the last end of the network is connected to the first end, so there is no endpoint, and the data transmission goes to unidirectional (clockwise or anticlockwise). It uses the token- passing mechanism of the token ring to transmit data from one node to a subsequent node. All the nodes get an equal chance or right to access the token. When the data signal reaches the destination node, it receives the information. Otherwise, this node again amplifies the signal to the next node and so on. In the case where the signal is not received by any node, it is absorbed by the source node. When the data are transmitted between two devices, the data packet flows through all the nodes in the network, so there is a chance of data loss. Thus, a repeater is used in every node of ring topology to prevent and reduce data loss. Advantages of ring topology • All data flow in one direction, reducing the chance of packet collisions. • A network server is not needed to control network connectivity between each workstation. • Data can transfer between workstations at high speed. • Additional workstations can be added without impacting the performance of the network. Disadvantages of ring topology • All data transferred over the network must pass through each workstation on the network, which can make it slower when compared to a star topology. • The entire network will be impacted if one of the workstations shuts down. • A ring topology architecture needs expensive hardware components for establishing the network. Points to Know • \"Communication refers to sending and receiving the information between two or more people, which helps us to share our feeling, idea, knowledge, instruction, etc. with each other.\" • Telecommunication, or telecom, is the transmission of signals over long distances. This allows people to quickly communicate with others across the street, city or across the globe. • Data communication is defined as a subset of telecommunication involving the transmission of data to and from computers and components of computer systems. • Elements of data communication are data, sender, medium, receiver and protocols. 30 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 • Modes of transmission are simplex Mode, half-duplex Mode, and full-duplex Mode. • To transmit data, it needs a signal called data transmission signal which is an electric current or electromagnetic field. • Conversion of digital signal to analog signal is called modulation and conversion of analog signal to digital signal is called demodulation. • Bandwidth describes the rate of data transmission to your computer from a website or internet services within a specific time. • Communication media are also called transmission media. They function as a transmission channel. It is a pathway that carries the information from sender to receiver. • Wired or guided media or bound transmission media are the cables that are tangible or have a physical existence and are limited by the physical geography. • Wireless communication involves a non-physical link to establish communicating wirelessly between two or more devices. • A computer network is a connection of two or more computers or devices in order to share resources such as printers and storage devices, computer programs, files, or electronic communication signals. • A network server is a computer designed to process, request, and deliver data to other (client) computers over a network. • Clients are computer devices that access and use the network as well as share network resources. • A hub is a hardware device that shares the network connection between multiple devices. • A switch is a hardware device that connects multiple devices on a computer network smartly than a hub. • A router is a network layer hardware device that transmits data from one LAN to another if both networks support the same set of protocols. • The gateway is the network node that connects two different networks using different protocols. • Repeaters are network devices operating at the physical layer of the OSI (Open Systems Interconnection) model that amplify or regenerate an incoming signal before retransmitting it. • The cable is also known as a data cable. It is commonly called Ethernet cable. It is used for connecting a device to transmit the data from one computer to another computer in the network. • NIC is a hardware component, typically a circuit board or chip, which is installed on a computer in order to connect to a network. • A Local Area Network (LAN) is a group of computer and peripheral devices which are connected in a limited area such as school, laboratory, home, and office building. • MAN is a computer network that connects computer across an entire city or a small region. • WAN covers a wide area which may span across provinces and even a whole country. • A computer architecture is a design in which all computers on a computer network are organized which includes physical and logical design. • The three most popular computer architectures are centralized computing network, client-Server architecture, and P2P (Peer to Peer). • The basic three network topologies are bus topology, star topology, and ring topology. Approved by Curriculum Development Center (CDC) 31

Network & Telecommunication Terms to Know Telecom : The exchange of information over significant distances by electronic means. It is the short form of telecommunication. Telegraph : A system in which information is communicated over a wire with a series of electrical current pulses. Analog Signal : A continuous measurement or transmission of a signal. Digital Signal : A signal that is being used to represent data as a sequence of discrete values. Data : Raw information that has been translated into a form that is efficient for movement or processing. Signal : An electrical or electromagnetic current that is used for carrying data from one device or network to another. Modulation : The process of changing digital data signal to analog data signal. Demodulation : The process of changing analog data signal to digital data signal. Baseband : The original frequency range of a transmission signal before it is modulated. Broadband : A high-speed internet connection which allows to enjoy everything the internet has to offer. Antenna : A device to transmit and/or receive electromagnetic waves. Wireless : No physical wired connection between sender and receiver of the network. Frequency : The number of waves that pass a fixed point in unit time. Laser Diode : A semiconductor device that converts electrical energy into light. Password : A string of characters used for authenticating a user on a computer system. Protocol : A set of rules that allows electronic devices to communicate with each other. Unidirectional : Moving or operating in one direction only (clockwise or anticlockwise) Medium : A medium is any channel means by which information is transmitted between sender and receiver. Node : A computer or device connected to a network. Unicast : A single, direct request sent from one host to another Multicast : In computer networking, group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Broadcast : Transmitting a packet that will be received by every device on the network. Crosstalk : Unwanted signal in a communication channel. Metal foil : Thin sheet of leaf made by aluminium or copper. Ground reference : A very low resistance and inductance wire which is used to measure the voltage. Datagram/packet : A block of data transmitted across a network. 32 Approved by Curriculum Development Center (CDC)

Worksheet Smart Computer Science Book-10 Objective Questions Questions types marked by * are just for testing 1. Fill in the blanks: higher ability but can enhance the knowledge for SEE. a. Telephone was developed in ...................... b. ................................ modems are circuit boards that plug into one of the expansion slots on the motherboard. c. .............................. describes the rate of data transmission. d. .............................. media are the cables that are tangible or have physical existence. e. UTP comes in ..................................... categories. f. ..................... and .................... UTP cables are used in telephone communication. g. ................................. cable is a two-conductor cable. h. .......................... wave is a data transmission media in wireless communication. i. Two types of radio frequency are ........................... and ......................... j. Most communication satellites are placed in geo-stationary orbits .................. ..................... above Earth’s Equator. k. Bluetooth covers ...................... meters maximum distance. l. ............................ is a low power wireless communication. m. In WiFi setup system, ................. works as a communication hub wirelessly. n. ............................ is known as signal boosters or signal extenders. o. ............................. are the interface between NIC of computer and cable. 2. Write 'T' for true and 'F' for false statements: a. Communication can always be two way. b. External modem is connected to the computer through serial or USB port. c. Bandwidth is generally measured in bits per second. Approved by Curriculum Development Center (CDC) 33

Network & Telecommunication d. The amount of bandwidth determines the efficiency and speed of your internet activities. e. Twisted pair cable is used to connect devices to a short distance. f. STP is harder to install when compared with UTP. g. Gateway is the network node that connects two different networks using same protocols. h. The bandwidth of the cable depends upon the category. i. CAT-3 to CAT-6 cables are used for computer network data communication. j. Two conductors of coaxial cable are separated by an insulator. k. Coaxial cable is a variable electronic resistance transmission cable. l. Fiber optic works on the properties of light. m. Data are transferred at the speed of light with the fiber optic. n. Satellite creates the greatest network of communication. o. The laser communication system uses wires and cable connection. p. Any blockage or interruption cannot be resisted by the laser communication system. q. Bluetooth uses the radio wave to establish the connection and share the information. r. Wi-Fi networks need to be protected with password for the purpose of security. s. Network operating system software is stored in the client computer. t. A router is a kind of gateway of the data transmission. u. The router is an intelligent device. v. A gateway connects multiple dissimilar networks using different protocol. w. NIC is also called an Ethernet card. x. Gateway is also called a protocol converter. y. All the connected computers function as a server and workstation in the P2P architecture. z. In the star topology, if any node is failed, it affects other nodes. za. The ring topology uses the token passing method to transmit data. 34 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 3. Mark the correct option: a. Telephone is developed by: ii) Alexander Stepanovich Popov i) Alexander Graham Bell iii) William Shockley iv) Vladimir Kosmich Zworykin b. Data communication is performed in the form of document which may be : i) Text ii) Video iii) Audio iv) Images v) All of these c. One way communication medium: i) Radio ii) Television iii) News Paper iv) All of these d. Two way communication: i) Internet Chatting ii) Video Conferencing iii) Telephone Call iv) All of these e. Element of data communication: i) Data ii) Sender iii) Protocol iv) All of these f. Transmission signal: i) Analog ii) Digital iii) Both i) & ii) iv) None of these g. Communication media include: i) Cable ii) Waves iii) Both i) & ii) iv) None of these h. Data are transmitted through ii) Electromagnetic signal i) Electrical Signal iv) None of these iii) Both i) & ii) i. Types of communication media: i) Guided ii) Unguided iii) Both i) & ii) iv) None of these j. Wired or guided media are: i) Twisted pair ii) Coaxial cable iii) Fiber optic iv) All of these k. RJ-45 connector jack is used for the i) CAT-5 ii) CAT-6 iii) CAT-7 iv) Both i) and ii) l. UTP cables cover the standard maximum distance: i) 100 mt. ii) 50 mt. iii) 150 mt. iv) 300 mt. m. UTP cables have a maximum standard data transmission speed of: i) 100 mbps ii) 50 mbps iii) 150 mbps iv) 200 mbps n. Connectors used with fiber optic are: i) ST ii) FC iii) SMA iv) All of these o. Data transmission rate of optic fiber: ii) Millions of mbps i) Bilions of mbps iv) Hundreds of mbps iii) Thousands of mbps p. Wireless transmission uses: Approved by Curriculum Development Center (CDC) 35

Network & Telecommunication i) Microwave ii) Radio wave iii) Infared wave iv) Satellite communication v) All of these q. Microwave operates at high operating frequencies of: i) 300 MHz to 300 Ghz ii) 300 Ghz to 300 MHz iii) 30 Hz to 300 GHz iv) 300 GHz to 30 Hz r. Infrared wave sends the signal using: i) Infrared light ii) Radio frequency iii) Microwave iv) All of these ii) Windows server series s. Network operating system software are: i) Novel Netware iii) Linux iv) All of these 4. Write the full forms of : TV ................................................................ WAN ................................................................ USB.............................................................. CPU ................................................................. bps .............................................................. ALU ................................................................ mbps............................................................ NIC .................................................................. STP ............................................................. TCP ................................................................. CAT-6........................................................... IP ..................................................................... RJ-45 ........................................................... SMTP .............................................................. BNC ............................................................. HTTP ............................................................... ST ................................................................ ARP ................................................................. FC................................................................ POP ................................................................. LC ................................................................ PPP ................................................................. SC ............................................................... CDP.................................................................. RF ............................................................... VOIP................................................................. GHz.............................................................. IPX/SPX........................................................... IR ................................................................. Net BEUI ......................................................... Wi-Fi ............................................................ DHCP .............................................................. FTP ............................................................. DNS ................................................................. MAC............................................................. DSL ................................................................. LAN ............................................................. SoNET ............................................................. OSI .............................................................. ATM ................................................................. Modem ........................................................ ISP .................................................................. IP ................................................................. P2P ................................................................. MAN ............................................................ EMI ................................................................ 36 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 5. Write the terms for the following: l. A protocol that is used for searching and retrieving documents from remote sites. a. Physical components and devices used to connect the computer in the network Ans:......................................... environment. m. A set of rules and guidelines for sending and Ans:......................................... receiving information among computers and b. A computer designed to process, request, other electronic devices in the network. and deliver data to another computer over a Ans:......................................... network. n. The interface between the NIC of the Ans:......................................... computer and the cable which passes the c. A group of files that enable one or more data from one computer to another. hardware devices to communicate with the Ans:......................................... computer's operating system. o. Physical media are used for connecting a Ans:......................................... device to transmit the data from one computer d. A group of computer and peripheral devices to another computer in the network. which are connected in a limited area. Ans:......................................... p. Devices that amplify or regenerate an Ans:......................................... e. A computer network across an entire city or a incoming signal before retransmitting it. small region. Ans:......................................... q. Technology that connects two dissimilar Ans:......................................... f. All the computers and networking devices networks using different protocols. are connected in a circular path or closed Ans:......................................... loop. r. A device that connects different networks Ans:......................................... having the same set of protocols. g. All the computers and networking devices Ans:......................................... are connected to a single hub using a point- s. A device that delivers the message to the to-point connection. correct destination based on the physical Ans:......................................... address present in the incoming message. h. The physical or logical layout of a network. Ans:......................................... Ans:......................................... t. A device that will broadcast the request to the i. Network covers a wide area which may span entire network. across provinces and even a whole country as well as out of the country. Ans:......................................... u. A node that accesses and uses the network Ans:......................................... j. All the computers are connected with every as well as shares network resources. computer in the computer network. Ans:......................................... v. The connection of two or more computers Ans:......................................... k. A device connected to a network. and devices that are linked in order to share resources. Ans:......................................... Ans:......................................... Approved by Curriculum Development Center (CDC) 37

Network & Telecommunication w. Low power wireless communication system, Ans:......................................... that is used by various electronic devices like zh. The signal varies over a continuous range smartphones, laptops, tablets, etc. that contains a time-varying quantity. Ans:......................................... x. Short-range wireless communication Ans:......................................... zi. Mode of communication where data can be technology that allows devices to transmit data or voice wirelessly over a short distance. transmitted in both directions simultaneously. Ans:......................................... Ans:......................................... y. Self contained long-distance wireless zj. Mode of communication where data flow in communication technology which is widely only one direction from the sending device to spread all over the world to connect users. receiving device. Ans:......................................... Ans:......................................... z. In the communication system, the signals are zk. Mode of communication where data can be transmitted from the wireless transmitter to a transmitted to both directions but only one wireless receiver without any interruption or direction at a time. blockage. Ans:......................................... Ans:......................................... zl. A hardware device that receives data and za. The technology which can transmit data information sent by the sender. signal through the air without any cable or wires or other electronic conductors. Ans:......................................... zm. The path where data are traveled during the Ans:......................................... zb. Waves that are used for very short-range transmission. communication purpose such as television Ans:......................................... and its remote. zn. A primary element that is to be transmitted or Ans:......................................... communicated. zc. Two-conductor cable in which one conductor Ans:......................................... forms an electromagnetic shield around the zo. The transmission of signals over long other. distance through suitable media. Ans:......................................... zd. Wire pair covered with metal foil. Ans:......................................... zp. A subset of telecommunication involves the Ans:......................................... ze. A pathway that carries the information from transmission of data to and from computers and components of computer system. sender to receiver. Ans:......................................... Ans:......................................... zq. Sending and receiving the information zf. The rate of data transmission within a specific between two or more people. time. Ans:......................................... Ans:......................................... zr. The network model where every node has zg. A sequence of voltage pulses is represented equal right to access the data and use in binary forms of 0s and 1s. resources. Ans:......................................... 38 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 zs. Caballing patterns of computers and devices zu. The caballing pattern of computers and where every computer is connected to the devices where every node is separately common cable in the linear format. connected to a centrally located device. Ans:......................................... Ans:......................................... zt. The network architecture where at least one zv. The cabling structure or physical layout of server. computers on LAN. Ans:......................................... Ans:......................................... 5. Match the following: Repeater a. Group of interconnected computers Node b. Protocol CAT-5 c. Windows NT Network within the city d. Transmission channel Hub e. BNC Network f. Largest WAN FTP g. Boost the signals and forwards Network OS h. Computer or devices provided to user Optical Fiber i. RJ-45 Coaxial cable j. MAN Internet k. Center device in start topology Descriptive Questions 1. Write very short answer of the following questions: a. What is communication? b. What is telecommunication? c. What is data communication? f. What is transmission signal? g. What is bandwidth? h. What is communication media? j. What is twisted a pair cable? k. What is coaxial cable? l. What is fiber optic? Approved by Curriculum Development Center (CDC) 39

Network & Telecommunication m. What is wireless transmission media? p. What is satellite communication technology? q. What is a computer network? t. What is a router? v. What is a gateway? x. What is protocol? y. What is LAN? z. What is MAN? za. What is WAN? zb. What is network topology? zc. What is bus topology? zd. What is star topology? ze. What is ring topology? zf. What is packet or datagram? 2. Write short answer of the following questions: b. Why do we use modem in the telecommunication? d. Why do we use bluetooth technology? e. Why is client computer called workstation? f. Why is switch more intelligent than hub? g. Why is router called intelligent device? h. Why do we use repeater? i. Why is ethernet card used? j. Why is repeater used in every node of Ring Topology? k. What is the role of network operating system? l. What is network architecture? m. Write the five basic elements of data communication. n. Differentiate between half-duplex mode and full-duplex mode of data transmission. o Differentiate between guided and unguided media. p. Differentiate between STP and UTP. q. Differentiate between client and server. r. Differentiate between hub and switch. s. Differentiate between router and switch. t. What is centralized computing network? Write its advantages and disadvantages. u. What do you mean by client server architecture? v. Differentiate between centralized computing network architecture and client server architecture. w. In which places is P2P architecture more suitable? x. Write the advantages and disadvantages of P2P architecture. 40 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 y. Which method is used in Ring Topology to transmit data? z. What is wireless communication technology? za. Write the working principle of bus topology. zb. What is signal reflection in Bus Topology? 3. Write short note: b. Analog signal c. Digital signal a. Simplex mode e. Radio wave f. Infrared wave d. Microwave h. Wi-Fi g. Bluetooh Case Study and Application-based Questions* 1. Saugal Trading Pvt. Ltd. is planning to connect 40 computers in the corporate office building. Now, on the basis of this relation, answer the following questions: a. Which type of network will be formed after connecting these computers? Ans: ......................................................................................................................................................... b. Recommend the most economical cable with a high data transfer speed that can be used to connect these computers. Ans: ......................................................................................................................................................... c. Which topology is suitable for such a network? Ans: ......................................................................................................................................................... d. Which architecture would you suggest to Saugal Trading? Ans: ......................................................................................................................................................... e. List out the devices required to establish this network. Ans: ......................................................................................................................................................... 2. Jogindar Mahato has a desktop, laptop, printer, mobile phone and tablet. He is willing to connect all these devices under a network: a. Which type of Network will be formed ? Ans: ......................................................................................................................................................... b. Which topology is suitable for such a network? Ans: ......................................................................................................................................................... c. Which architecture would you suggest to Jogindar? Ans: ......................................................................................................................................................... d. Which type of media will be used to transfer data from one device to another ? Ans: ......................................................................................................................................................... Approved by Curriculum Development Center (CDC) 41

Network & Telecommunication e. List out the devices required to establish this Network. Ans: ......................................................................................................................................................... .......................................................................................................................................................... 3. All the 25 computers in an organization are connected on a network so that they can use one printer and access the internet through the same modem. Now, answer the following questions on the basis of this relation: a. Why is it a good idea to connect all the computers in a network? Ans: ......................................................................................................................................................... b. Which type of Network will be established ? Ans: ......................................................................................................................................................... c. List out the devices required to establish this Network. Ans: ......................................................................................................................................................... 4. Identify the devices used for each of the following: a. Hardware component used to connect computers in a network. Ans: ......................................................................................................................................................... b. Every computer should have this network component card. Ans: ......................................................................................................................................................... c. UTP wire connector that is commonly used to connect the network interface card with the hub. Ans: ......................................................................................................................................................... 4. Udayapur Cement Industries Ltd. wants to connect all the offices with computer network such as corporate office Kathmnadu, factory site Jaljale and other regional offices of all over the country. a. Which type of network is formed? Ans: ......................................................................................................................................................... b. Make a diagram of the network in chartaper. Ans: ......................................................................................................................................................... c. Which type of technology is used to transmit the data in long range? Ans: ......................................................................................................................................................... d. List out the devices to establish this network. Ans: ......................................................................................................................................................... .......................................................................................................................................................... 42 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 5. Raghubir Mahaseth has got the following electronic gadgets: i) Laptop ii) Mobile Phone iii) Tablet iv) Speaker There is no wireless or wired connected network and internet connection. Now, Raghubir has to transfer some images and music videos from laptop to tablet, Mobile phone and vice-versa. He wants to play the speaker without wired connection from laptop, tablet or mobile phone as he likes. a. Which type of technology do you suggest Raghubir to solve this problem instantly? Ans: ......................................................................................................................................................... Activity* 1. Organize the interclass speech competition on the topic \"Communication is most important for our success\" . School Bulletin 2. Write an article for your school's news bulletin on the topic \"Internet is a Biggest WAN \" . 3. Arrange your class into three groups and 43 organize the chart paper or digital presentation about the assigned topic: a. Network Architectures b. Network Topologies c. Network categories (LAN, MAN and WAN) Approved by Curriculum Development Center (CDC)

Internet and Services CHAPTER Internet and Services 2 Chapter Includes • Introduction to Internet • Internet Services : WWW, E-mail, Telnet, Searching, File Transfer, Video conferencing, online banking, E-commerce, News group, Internet Telephony • Internet Connection. • Internet Service Provider. INTRODUCTION The Internet is a global communication system of interconnected computer networks that uses the standard Internet protocol (TCP/IP) to link billions of devices worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks of local to global scope linked by a broad array of electronic wireless and optical networking technologies. The Internet allows exchanging information between two or more computers on a network. Thus the Internet helps to exchange messages through e-mail, chat, video and audio conferences, etc. It has become a mandatory factor to perform day-to-day activities like bill payment, online shopping, and surfing, tutoring, working, communicating, e-learning, etc. All these tasks can be performed by connecting a computer to the Internet, which is also called going online. When someone says a computer is online, it is just another way of saying it is connected to the Internet. The first working prototype of the Internet came in the late 1960s with the creation of ARPANET (Advanced Research Projects Agency Network). Originally funded by the U.S. Department of Defense, ARPANET used packet switching to allow multiple computers to communicate on a single network. On October 29, 1969, ARPANET delivered its first message: a “node-to-node” communication from one computer to another. From 1992 AD, the Internet was openly used throughout the world. In Nepal, Internet service was started by Mercantile company in 1994 AD. INTERNET SERVICES The main services provided by the internet are: World Wide Web (WWW)  World Wide Web, which is also known as a web, is a collection of websites or web pages stored in the web servers and connected to local computers through the Internet. These websites contain text pages, digital images, audios, videos, etc. 44 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Users can access the content of these sites from any part of the world over the Internet using their devices such as computers and cell phones with the help of a web browser. The WWW, along with the Internet, enables the retrieval and display of text and media to your device using HTTP (HyperText Transfer Protocol). In conclusion, WWW is the bank of information where web documents and web resources are recognized by using a URL (Uniform Resource Locators). Web information is always stored and passed over in the form of hypertext and hypermedia. A web document is prepared using HTML (HyperText Markup Language). The World Wide Web was invented by a British scientist, Tim Berners-Lee in 1989 AD. He was working at CERN (Nuclear Research) laboratory at that time. Originally, it was developed by him to meet the demand for automated information- sharing between scientists in universities and institutes around the world, so that they could easily share the data and results of their experiments and studies with each other. Electronic Mail E-mail is one of the most popular services on the Internet. It is an Internet-based online postal service that is used to send and receive messages to one or more recipients across the Internet. It uses the two mail protocols which are POP (Post Office Protocol) to receive an e-mail and SMTP (Simple Mail Transfer Protocol) to send an e-mail. Similar to physical mail, an e-mail requires an address for both the sender and recipient in order to send a message successfully. Mail addresses are strings separated by the character \"@\" sign. The right-hand part describes the domain name and the left-hand part refers to the user who belongs to that domain like [email protected]. Approved by Curriculum Development Center (CDC) 45

Internet and Services You can get the e-mail service from the e-mail based websites like google.com, yahoo.com, hotmail.com, etc. ISP (Internet Service Provider) and web hosting service providers also provide the e-mail services. Adavantages of E-mail • E-mail is a free communication tool that can be sent 24 hours a day, 365 days a year. • E-mails are delivered extremely fast as compared to traditional postal mail. • E-mail is a cheaper service as compared to traditional mail. • E-mail allows for the attachment of multimedia files like photos, audios, and videos. Telnet (Teletype network) Telnet is a protocol that allows you to connect and login into remote computers called hosts over a TCP/ IP network such as the Internet. Using Telnet client software on your computer, you can make a connection to a Telnet server i.e. the remote host. Once your Telnet client establishes a connection to the remote host, your client becomes a virtual terminal, allowing you to communicate with the remote host from your computer. In most cases, you'll need to log in as the remote host, which requires that you have an account on that system. Occasionally, you can log in as a guest or a public account, without having a personal account. Telnet also has a command-line interface. Command-line Telnet clients are built into most versions of macOS, Windows, Unix, and Linux. To use these clients, a user can go to their respective command lines. AnyDesk, Ammyy Admit, Windows Remote Desktop are some popular remote accessing software. File transfers: File transfer is sending of one or more digitized files from one device to another device over the Internet. It is a service available on the Internet which allows to download and upload files from one computer to another computer i.e. client computer to remote computer. To upload and download the files in/from a remote 46 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 computer, the client computer needs an FTP client software which helps to connect it with the FTP server from where a user can download and upload files. FTP (File Transfer Protocol) is a standard Internet protocol for transmitting files between computers on the Internet over TCP/IP connections. FTP is a client- server protocol where a client asks for a file, and the remote server provides it. Search Engine A search engine is a web-based software that can be accessed on the Internet. It searches a database of information according to the user's query. The engine provides a list of results that best match what the user searches for. Today, there are many search engines available on the Internet, each with its own abilities and features. The first search engine ever developed is Archie, which was used to search for FTP files, whereas the first text-based search engine is Veronica. Currently, the most popular and well-known search engine is Google. Other popular search engines include AOL, Ask.com, Baidu, Bing, DuckDuckGo, and Yahoo. Internet Relay Chat IRC (Internet Relay Chat) is a protocol for real-time text messaging between Internet-connected computers or devices. It is mainly used for group discussion in chat rooms called “channels”, although it supports private messages between two users. Some of the chatting services software are Viber, WhatsApp, Facebook Messenger, etc. Video-Conferencing Video-conferencing, also known as Video-telephony, and video tele-conferencing, is the two-way or multipoint reception and transmission of audio and video signals by people in different locations for real time communication. This technology is particularly convenient for business users in different cities, or Approved by Curriculum Development Center (CDC) 47

Internet and Services even different countries because it saves time, expenses, and reduces difficulties associated with business travel. Uses of video-conferencing include holding routine meetings, negotiating business deals, and interviewing job candidates. Group video conference service is provided by Google Meet, Zoom, GoToMeeting, Skype, etc. Internet banking Internet banking is the system that provides the facility to conduct financial and non- financial functions from the customer’s Internet banking account. The user can transfer funds from his account to other accounts of the same or different bank using a website or an online application. The customer uses a resource and a medium to conduct financial transactions. The resources that a customer uses might be an electronic device like a computer, a laptop, or a mobile phone, and the bank’s application. The Internet is the medium that makes Internet banking possible. Features of Internet Banking The common features of Internet Banking are as follows: • The customer can view account statements. • The customer can check the history of the transactions for a given period by the concerned bank. • Bank statements, various types of forms, applications can be downloaded. • The customer can transfer funds, pay any kind of bill, recharge mobiles, DTH (Direct-to-Home) connections, etc. • The customer can buy and sell on e-commerce platforms. • The customer can invest and conduct trade. • The customer can book transportation tickets, travel packages, medical care, etc. E-Commerce E-commerce is the buying and selling of goods, products, or services over the Internet. E-commerce is also known as electronic commerce or Internet commerce. These services are provided online over the Internet network. 48 Approved by Curriculum Development Center (CDC)

Smart Computer Science Book-10 Transaction of money, funds, and data are also considered to be E-commerce. These business transactions can be done in four ways: • Business to Business (B2B), • Business to Customer (B2C), • Customer to Customer (C2C), • Customer to Business (C2B). The standard definition of E-commerce is a commercial transaction that is performed over the Internet. Online stores like Amazon, Flipkart, Shopify, Myntra, eBay, Quikr, and Daraj are examples of E-commerce websites. Newsgroup A newsgroup is an Internet-based discussion forum around an individual, entity, organization, or topic. Newsgroups enable remotely connected users to share, discuss and learn about their topic of interest by exchanging text messages, images, videos, and other forms of digital content. Newsgroups are typically found on Usenet (User Network) where millions of users read posts, or articles, using software called a newsreader. Users can make comments and ask questions in response to the posts. To access the newsgroup, it needs a Usenet (User Network) subscription. Most Usenet service providers offer monthly access charges. Alt.politics, Alt.physics, Comp.lang, C++ are common examples of newsgroup. Internet Telephony Internet telephony refers to all features of traditional telephony (phone calls, fax, voicemail, etc.) where all calls and data are sent over the Internet rather than traditional landlines. Voice over Internet Protocol (VoIP) is placed for phone calls over the Internet. Examples of Internet telephony services applications are CoolTalk, Approved by Curriculum Development Center (CDC) 49

Internet and Services Netmeeting, Skype, Viber, WhatsApp, Messanger, etc. It is cheaper and efficient in comparison to PSTN (Public Switched Telephone Network) which is commonly known as a landline telephone. INTERNET CONNECTION Internet connection is the ability of individuals and organizations to access the Internet using computer terminals, computers, and other devices, as well as to access services such as the World Wide Web. There are different types of Internet connection technologies, one of the most common connections is Asymmetric Digital Subscriber Line (ADSL). Other popular technologies are ISDN(Integrated Services Digital Network), cable line, leased line, satellite connection, fiber-optic connection, Digital Subscriber Line (DSL), etc. ISP (INTERNET SERVICE PROVIDER) An Internet service provider is an organization that provides services for accessing, using, or participating in the Internet. Internet service providers can be taken into various categories, such as commercial, community-owned, non-profit, or privately owned. ISP provides a client with Internet access, usually for a fee. Without an ISP, a user wouldn’t be able to shop, access websites, find information, communicate and share information with others through the Internet. Connecting to the Internet requires specific telecommunications, networking, and routing equipment. ISPs allow users to access networks that contain the required equipment, enabling users to establish Internet connectivity. ISPs are responsible for making sure that their clients can access the Internet, routing Internet traffic, resolving domain names, and maintaining the network infrastructure that makes Internet access possible. Nepal Telecom (NTC), World Link, Classic Tech, and Vianet are some of the popular ISPs in Nepal. 50 Approved by Curriculum Development Center (CDC)