Book 10 Revised by Krishna K. Shrestha Oasis Radiant Computer Science Oasis Publication (P) Ltd. Anamnagar, Kathmandu Phone :0977-01-4313205 Approved by the Government of Nepal, Ministry of Education, Science and Technology, Curriculum Development Centre (CDC), Sanothimi Bhaktapur
Oasis Radiant Computer Science Class 10 Revised by Krishna K. Shrestha Layout Design: Zeeta Computer Service Pvt. Ltd. Ghantaghar, Kathmandu Publisher: Oasis Publication (P) Ltd. Anamnagar, Kathmandu Nepal Tel: 977-01-4313205 www.oasispublication.com.np Printed in Nepal © Publisher First edition : 2017 Second edition : 2020 Revised edition : 2022 This book belongs to... Name : Mr./Miss ...................................................... Class : ................ Section. ............ Roll No....... School : ...................................................................... ....................................................................................
Acknowledgement We are in the 21st century. This is the age of Information and Communication Technology (ICT). ICT has become an integral part of our daily life. It facilities business people, academicians, students, and professionals in the banking and other sectors. Computer education has become a fundamental right of children. Today’s children need the knowledge of computer, from basic to advanced level, to cope with the changes unfolding now and coming in the future. The Curriculum Development Centre (CDC) of Nepal government has prescribed the syllabi and course outlines for computer education from primary to higher secondary level. Students are deprived of quality computer education due to the lack of quality course books and limited access to the computer system in schools. To address this issue, I have developed a complete series of computer books under the banner “Oasis Radiant Computer Science” from grade I to grade XII. I have devoted a lot of time in the research and development of this book. It provides a comprehensive and balanced coverage of the CDC syllabus. All this has been possible thanks to the comprehensive support I received from my family members, colleagues, students and teachers. I would like to acknowledge all who have directly or indirectly encouraged me to prepare this book for their contribution. Specially, my thanks go to the students and teachers of different schools for their regular interactions with me and inspirations they gave me to prepare this book. I am grateful to my parents Tek Nath and Chisa Maya Adhikary, family members Lachhima Adhikary, Jagan Adhikary, Sarashwati Adhikary and lovely kids Samridhi, Sampada, Prasamsha, Ballavi, Ragavi, Suyash and Suyasha Adhikary for their valuable contributions from their place as I prepared this book. OASIS PUBLICATION family deserve kudos for their innovative help in preparing and publishing this book. Finally, all the suggestions and comments are acknowledged. Thanking all, Author
Area and Contents Area Contents Tentative No. of Classes Th Pr 1. Introduction Technology Fundamentals (1.1) Networking & Telecommunications (1.1.1) Introduction to Networks (i) Communication Media (Guided & Unguided Media) (ii) Elements of Network (NIC Card, Connectors, Hub, Bridge, Switch, Router, Gateway, Repeater, Modem) (iii) Types of Network LAN, MAN, WAN (iv) Network Architecture Peer-to-peer Network, Client-Server Network, Centralised Network (v) Topologies (Bus, Star, Ring) (vi) Protocols (Definition and Example only) (vii) Advantages & Disadvantages of Network (viii) Internet and its services (1.2) Ethical and Social Issues in ICT Digital Citizenship, Digital Footprint, IT policy 2072, Electronic Transaction Act, Opportunities and threats in Social Media (1.3) Computer Security (a) Computer security, Information security, security threats, malicious codes (b) Security mechanisms (i) Authentication systems: Password, biometric (ii) Firewalls (iii) Cryptography : Encryption, Decryption (iv) Antivirus software (v) Backup System (a) Hardware Security (i) Regular Maintenance (ii) Insurance (iii) Free from dust (iv) Fire (v) Thief (vi) Air Condition system (vii) Power protection device (Volt guard, Spike guard, UPS) (1.4) E-Commerce (i) Introduction (ii) Benefits and Limitations of E-Com- merce (iii) Types of E-Commerce: B2B, B2C, C2C (iv) M-Commerce (v) Online Payment (1.5) Contemporary Technology Cloud Computing, Artificial Intelligence, Virtual Real- ity, E-Governance, Mobile Computing, Internet of things (IOT) (1.6) Number System (a) Binary Arithmetic (addition, Subtraction, Multiplication, Division) (b) Base Conversion (Decimal, Octal, binary and hexadecimal) 34
2. Database Management System (2.1) Introduction (i) Data and Information, Database Concept, Database Management Concept (ii) Files, Data type, Record, Table (2.2) Creating a Database using MS-Access (i) Creating a new Database (ii) Creating a new Table by design view, Saving and creating a Primary key (iii) Adding and deleting fields (iv) Editing Field name, Data type, Field size and Index (2.3) Entering and Editing Data (i) Adding, Editing, Inserting, Deleting and sorting records (ii) Adjusting Column widths and hiding columns (2.4) Querying Database (i) Select Query (ii) Update Query (iii) Delete Query (iv) Insert Query (criteria with maximum two conditions) (2.5) Creating and using forms (i) Creating Form by using wizard, Entering and Editing Data using a from (2.6) Creating and Printing Reports (i) Printing the table data, Creating a Report Using the Report Wizards (ii) Printing a Report 17 29 3. Programming in QBASIC (3.1) Modular Programming (i) Concept of modular programming approach (ii) Main module, procedure modules (function and sub procedures) (iii) Parameters (Concept of Local & Global variables) (iv) Writing and calling function procedure (v) Define and call procedures (FUNCTION... END FUNCTION, SUB... END SUB,CALL) (3.2) File processing (file handling) (i) Data file (sequential only) (ii) File modes (output, input, append) (iii) File processing activities • Opening a file • Writing to a file • Reading a file • Appending records to a file • Closing file Statements and Functions to be covered: File Input / Output Management statement and functions (OPEN, CLOSE, WRITE#, PRINT#,INPUT#,INPUT$ LINE INPUT#,EOF,NAME,KILL, FILES,CHDIR,MKDIR,RMDIR) 24 37 4. C- Programming 1. Introduction to C-Language Programming 2. Data types, operators 3. Keywords in C-Language 4. Input /Output using scanf & printf 5. Writing Programs using if and looping statements 10 19 85 85
Oasis Radiant Computer Science, Book 10 8 Contents Chapter Lesson Page No. 1 Networking & Telecommunication 9 2 Ethical & Social Issues of ICT 50 3 Computer Security 64 4 E-Commerce 75 5 Contemporary Technology 85 6 Number System 96 7 Database and Database Management System 112 8 Review of QBASIC Programming 185 9 Modular Programming 221 10 File Handling 254 11. Introduction to C Language 282
Approved by Curriculum Development Centre 9 Oasis Radiant Computer Science, Book 10 Chapter 1 Networking & Telecommunication ffl Introduction to networks. ffl Advantages, disadvantages and types of networks. ffl Topology and protocols. ffl Communication media. ffl The internet and its services. THIS CHAPTER COVERS :
Oasis Radiant Computer Science, Book 10 10 Approved by Curriculum Development Centre Networking and 1 Communication Chapter Introduction Communication means sending or receiving information. In ancient times, people used the beatings of drums, smoke signals, mirror reflection and homing pigeons for communication. With the advancement of science and technology, various devices were invented for communication. Different systems such as telegraph, fax, email and internet are used for communication. Telecommunication is a term derived from a Greek word that means “communication at a distance”. We use this term to mean communication of information represented in many ways: voice, data, graphics, images, video; in various formats: bytes, frames, packets; and communicated over various media: copper wires, fibre optics, the air, space. Telecommunication is defined as the exchange of information over significant distances by electronic means. A complete single telecommunication circuit consists of two stations, a transmitter and a receiver. The transmitter and receiver, at any station, may be combined into a single device called a transceiver. The medium of signal transmission can be electrical wire or cable (also known as “copper”), optical fibre or electromagnetic fields. The free-space transmission and reception of data by means of electromagnetic fields is called a wireless system. Data Communication Data communication is the process of exchanging data between two devices using wired and wireless transmission media. The process includes the transfer of data, the methods of transfer and preservation of the data during the transfer. Basically, there are five components of data communication. • Message: It is the information to be communicated. • Sender: Device that sends the message.
Approved by Curriculum Development Centre 11 Oasis Radiant Computer Science, Book 10 • Receiver: Device that receives the message. • Medium: Path that communicates the message from the sender to the receiver. • Protocol: A set of rules that coordinates the exchange of information. Both sender and receiver should follow the same protocol. Fundamental Characteristics of Data Communications The word data refers to information presented in the form of text, audio, visual, etc. Data communications mean the exchange of data between two devices using a transmission medium such as a wire cable. For data communications to occur, the communicating devices must be part of a communication system made up of a combination of hardware (physical equipment) and software (programmes). The effectiveness of a data communications system depends on four fundamental characteristics: delivery, accuracy, timeliness and jitter. Delivery The system must deliver data to the correct destination. Data must be received by the user and the device for further uses.
Oasis Radiant Computer Science, Book 10 12 Approved by Curriculum Development Centre Accuracy The system must deliver the data accurately. Data from destination and source should be in the same format. Timeliness The system must deliver data in a timely manner. Data delivered late are useless. In the case of video and audio, timely delivery means delivering data as they are produced, in the same order that they are produced and without any significant delay. This kind of delivery is called real-time transmission. Jitter Jitter refers to the variation in the data arrival time. It is the uneven delay in the delivery of audio or video data packets. Data Transmission Mode Transmission mode refers to the direction of signals flowing between two linked devices. There are two modes of data transmission: a. Simplex b. Duplex • Half duplex • Full duplex Simplex It is a unidirectional transmission. The information flows in one direction across the circuit. Only one side transmits the information and the other receives it. Television transmission is the best example of a simplex transmission.
Approved by Curriculum Development Centre 13 Oasis Radiant Computer Science, Book 10 Duplex It is a bidirectional transmission. In this mode, the information flows in two directions across the circuit. There are two types of duplex. Half Duplex: It is a two-way communication where each communication device can receive and transmit information but not at the same time. When one device is sending the signal, the other can only receive it at the time. Data communication on a networking system using cable is half duplex. Another best example is the walky talky, used by the traffic police. Full Duplex: It is a to-way communication where both communication devices transmit and receive data simultaneously using the same path. It uses same path for sending and receiving the data at the same time. Example: The general telephone system where the speaker on one side can transmit and hear the message at the same time using the same phone line. Communications media An important aspect of communication is the medium, which is the communication path between two devices. A communication medium is composed of one or more transmission media (plural of medium). Transmission media consist of materials or techniques capable of carrying one or more signals. Transmission media are available in two types: • Physical or wired or guided communication media • Wireless or unguided communication media
Oasis Radiant Computer Science, Book 10 14 Approved by Curriculum Development Centre Guided Media Guided Transmission Media use a “cabling” system that guides the data signals along a specific path. The data signals are bound by the “cabling” system. So it is also known as bound or wired media. Some of the guided media used in networking are: • Twisted Pair cable • Coaxial cable • Fibre Optics cable Twisted Pair It is a copper wire cable which consists of two insulated copper wires that are twisted together in a helical form. There are two types of twisted pairs: Unshielded Twisted Pair (UTP) cable and Shielded Twisted Pairs (STP). Both types consist of four pairs of colour-coded wires that have been twisted together and then encased in a flexible plastic sheath. • UTP: It is a common type of communication medium used for telephone system. It is suitable for voice and data transmission. It is insulated with a plastic insulation jacket. • STP: It has a metal foil covering that covers each pair of insulated conductors. The metal foil is used to prevent infiltration of electromagnetic noise. This shield protects the cable from external environment like electronic effects and magnetic effects. The purpose of twisting the wire is to reduce electrical interference from similar pairs. Twisted pairs can run approximately 100 metres without amplification, but for longer distances, repeaters are needed. Twisted pairs can be used for either analogue or digital transmission. The bandwidth depends on the thickness of wire and the distance travelled. According to the category of cable, it can carry 10Mbps, to 1000Mbps. We have different categories of twisted pair cable. These are: Category 5 (Cat5) and Category 6 (Cat6). Coaxial Cable It has a single centred conductor, which is made up of a solid copper wire. This conductor is surrounded by an insulator over which is a sleeve of metal mesh to
Approved by Curriculum Development Centre 15 Oasis Radiant Computer Science, Book 10 block any outside interference. This metal mesh is again shielded by an outer covering of a thick material known as jacket. It has a higher bandwidth than that of the twisted pair cable. It is available in a base band and broadband form. Base band coaxial cable is used for LAN (Local Area Networking) and broadband coaxial cable is used for TV cable network and other MAN (Metro Area Network) for internet connection. It can transfer the data with a speed from 40 Megabyte per Second (Mbps) to 1000 Megabyte per Second (Mbps). BNC (Bayonet Neill Concelman) is used to connect the Coaxial cable with computer. Fibre Optics Fibre-optic cabling uses either glass or plastic fibres to guide light impulses from the source to destination. The bits are encoded on the fibre as light impulses. The two types of cable discussed earlier can transfer data in the form of current but fibre optic cable can transfer data in the form of visible light. It consists of a thin glass fibre that can carry information in the form of light. An optical transmission system has three components: the light source, the transmission medium and the detector. The pulse of light indicates “1” bit and the absence of light indicates ”0” bit. The transmission medium is ultra thin fibre of glass. By attaching a light source to one end of an optical fibre and a detector to the other, we have a unidirectional data transmission system that accepts an electrical signal, converts and transmits it by light pulses, and then reconverts the output to an electrical signal at the receiving end. It can transfer data with very high speed because it has high bandwidth. It can transfer data with a speed of a few Gigabytes, or GBPS, to hundreds of GBPS. Unguided Media The wireless communication media are called unguided media. Unguided Transmission Media consist of a means for the data signals to travel but nothing to guide them along a specific path. The data signals are not bound
Oasis Radiant Computer Science, Book 10 16 Approved by Curriculum Development Centre to a cabling media and as such are often called Unbound Media. Some of the unguided media used in networking are as follows: Microwave System Communication Satellites Microwave Transmission It is a line of sight transmission. The transmit station must be in visible contact with the receiver station. This sets a limit on the distance between stations depending on the local geography. Typically, the line of sight due to the earth’s curvature is only 50km to the horizon. Hence, the repeater stations must be placed so the data signals can travel farther than the distance limit. Communication Satellite Communication satellites have some interesting properties that make them attractive for many applications. A communication satellite can be thought to be a big microwave repeater in the sky. It contains several “Transponders”, each of which listens to some portion of the spectrum, amplifies the incoming signal and then rebroadcasts it at another frequency to avoid interference with the incoming signal. The downward beams can be broad, covering a substantial fraction of the earth’s surface. Infrared (IR) Infrared is a type of electromagnetic wave of large wavelength and small frequencies than the visible light. Its frequency is low, so it has small penetrating power. It cannot penetrate an opaque medium. IR data transmission is also employed in short-range communication among computer peripherals and personal digital assistants (PDAs). Remote controls and IrDA Infrared Data Association (IrDA) devices use infrared emitting diodes (IEDs) to emit infrared radiation which is focused by a plastic lens into a narrow beam. The beam is modulated to encode data. The receiver uses a silicon photo diode to convert the infra radiation to an electric current. It is used in optic fibre communication, wireless LAN, computers, printers, TV and many other electronic devices.
Approved by Curriculum Development Centre 17 Oasis Radiant Computer Science, Book 10 Bluetooth A proposed radio frequency (RF) specification that many portable devices use for short-range wireless communications is called Bluetooth. With Bluetooth, devices such as laptop computers, handheld computers, cellular telephones, pagers, fax machines, and printers can wirelessly communicate with each other. To use Bluetooth technology, each device must include a transceiver chip and be within a specified range (about 10 meters but can be extended to 100 meters with additional equipment). Analogue message signals or digital data streams are combined into one signal over a shared medium. (i) Wi-Fi Wireless Fidelity is a type of wireless network technology used for connecting computers and other devices to the computer network and internet. The frequencies Wi-Fi works at are 2.4GHz or 5GHz, which ensure no interference with cellphones, broadcast radio and TV antenna. The two-way radios are encountered during transmission in the Wi-Fi system. Computer Networking A computer network is a group of computers or devices connected to share the network resources like files, printers and network services. A typical computer network consists of users Client Operating Systems like Windows and store their files inside a central network server. Computer networks are required for network communication and network resource sharing (printers, scanners, storage spaces). To build and connect computer networks, we need computers (Clients and Servers) and special network infrastructure devices.
Oasis Radiant Computer Science, Book 10 18 Approved by Curriculum Development Centre It is a collection of two or more computers which are connected to share the data and resources. The key term “Sharing” is the main feature of a networking system. Personal computers are powerful tools that can process and manipulate large amounts of data quickly but they do not allow users to share their data efficiently. Before networking, users needed either printed documents or copied files to disk to exchange and share the data which is called a standalone environment. It is impossible to communicate and share data between the computers using common database on these independent standalone computers. However two or more computers are linked together, using a cable that allows them to share data, and this is known as a networked environment. Computers in a networked environment are connected with different communication media such as cables, phone lines, microwaves, and satellites. Advantages • Networking provides cheaper and faster communication services. • It is easy to share the resources like data, software and hardware and network, etc. • It provides faster and cheaper data transmission between multiple computers. • It works as a tool for e-mail, teleconferencing, and videoconferencing, which facilitate communication. • It has flexible working conditions. • It helps to automate the office. • It provides centralised administration and control using central computer called server. • It helps to provide a collaborative work and remote job entry.
Approved by Curriculum Development Centre 19 Oasis Radiant Computer Science, Book 10 Disadvantages • It increases the installation and administrative cost. • It is difficult in a network to control and maintain the privacy of the people. • High chances of spreading the viruses through network. • It is very complicated to repair and maintain the network. • If the server is out of order, then all working computers will hang up and stop working. • Well-trained technical support is required. Elements of Computer Network To connect the computer to a network, we need the following devices: 1. Computers: We need some computers to make server and clients/ workstation on the computer network structure. The server computer is the main computer that controls and serves the data to the clients. • Server: The central host computer that serves the data to multiple computers and provides central control to the system is called a server computer. It serves the disk space, printer and other hardware devices, database etc. To make a server, we need the branded or high processing mainframe and minicomputer. • Clients: All the working computers attached to the computer network are clients. These are working terminals and get all types of resources from the server and these are controlled by the host computer. We can use assembled micro computers as the clients. 2. NIC (Network Cards): Network Interface Card popularly known as Network Card is essential to connect the computers. 3. Communication media: The path to transfer data from one computer to another is the communication medium. There are two types of communication media: wired and wireless. • Wired: These are bounded and physical communication media that can transfer data using some cables. Popular cables are twisted pair cable, coaxial cable, fibre optic cable etc. • Wireless: These are unbounded or unguided communication media that transfer data using microwave and electromagnetic signals. Popular wireless media are microwave, satellite, Bluetooth, etc.
Oasis Radiant Computer Science, Book 10 20 Approved by Curriculum Development Centre 4. Network connecting and signal conversion devices: Different devices like Hub, Switch, Bridge and Repeaters are used to connect the computer network. These are called network connecting devices. Different devices like Modem, Router, and Gateway are used to convert the signals from analogue to digital and vice versa. These are called signal conversion devices. • Repeaters: These are the signal amplifiers used to amplify weak signals and increase the length of LAN (Local Area Network). It links similar LANs. When Networking Operating Systems (NOS) are similar for any two or more LANs, then these LANs are called similar LANs. There are two types of repeater: Local Repeater and Remote Repeater. Local Repeater is used to connect two LANs separated by a small distance while Remote Repeater is used to connect LANs separated by large distances. • Bridge: It is a store and forward device used to connect different or similar networks (LAN) together. It is classified into two categories Local Bridge and Remote Bridge. Local bridge is a general type of bridge used to link LANs separated by a small distance. Remote Bridge is a type of bridge used to link large distance. In this case, two Bridges are connected through WAN (Wide Area Network). More than two LANs can connect through Bridge. • Router: It is a highly intelligent, protocol sensitive linking device used to link similar or dissimilar LANs. A router, which can be hardware, software, or both, is a device that connects two networks.
Approved by Curriculum Development Centre 21 Oasis Radiant Computer Science, Book 10 • Gateway: It is used to link dissimilar LANs. It also performs all functions of Bridge and Router. It is slower than Bridge and Router because it converts the entire protocol of one network to another. When we connect Ethernet (LAN) to token ring (LAN), Gateway converts Ethernet protocol into token ring protocol. • Hubs: The hub is the standard and important component of networking which is used to connect computers. Hub is used to receive incoming data, amplify and distribute them. 5. Communication software: Different software like Windows and Linux are used to administrate the network structure. Types of Computer Network A computer network is an interconnection of various computer systems located at different places. In a computer network, two or more computers are linked together with a medium and data communication devices for the purpose of communicating data and sharing resources. The computer that provides resources to other computers on a network is known as the server. In the network, the individual computers, which access shared network resources, are known as workstations or nodes. Computer Networks may be classified into two types according to the geographical area and the architecture. 1. On the basis of architecture • Peer to peer network • Client server network • Hybrid network 2. On the basis of geographical location • LAN (Local Area Network) • WAN ( Wide Area Network) • MAN ( Metropolitan Area Network) On the Basis of Architecture The networking structure is the combined form of networking topology and mode of data transmission from sender to receiver or vice-versa. Networking is a technology of data transmission and several techniques are applied to transmit data. It is essential to carefully choose or select which type of network one needs. The choice should be made upon the user’s requirements and budget.
Oasis Radiant Computer Science, Book 10 22 Approved by Curriculum Development Centre Peer-To-Peer Architecture The technique of data transmission from node to node in which each node behaves like a temporary server is called peer-to-peer architecture. There are no powerful servers and all are peers or equals. In the peer network, users simply share disk space and other resources, which is good for small and simple networks. If data packet transmitted from A has to reach the destination node C, the data packet first goes to node B, if data address is not matched with B, then it is transferred to node C, where data address is matched, and communication is started. When communication is established between two nodes, the remaining nodes are free, with no problem of traffic. Advantages of Peer-To-Peer Network • Easy to install and configure. • Individual machines do not depend on the presence of a dedicated server. • Individual users control their own shared resources. • It is inexpensive to purchase and operate. • No additional software or hardware beyond a suitable operating system is needed. • No dedicated administrators are needed to run the network. • It works best for network with 10 or fewer users. Disadvantages of Peer-To-Peer Network • Network security applies only to a single resource at a time. • Users may be forced to use as many passwords as there are shared resources. • Each machine must be backed up individually to protect all shared data. • There is no centralised organisational scheme to locate or control access to data. • Not suitable for more than 10 users.
Approved by Curriculum Development Centre 23 Oasis Radiant Computer Science, Book 10 Client Server Architecture The client-server architecture is a type of networking structure in which workstations or nodes are connected with main server or host. The packet of data sent by any computer, at first reaches the server, and is then passed to each local computer. The local computer is called node or client. If address of packet is matched with node, it is delivered to that node. The server or host behaves like a distribution station. Servers are of various types depending upon the type of function they perform like File server, Printer server, Application server, Message server, Database Server, Web server, etc. where each server is dedicated to a particular function. A network can have any number of servers ranging from 1 to several hundreds of servers (server-farms), depending upon the size and requirements of the network. Servers are usually most powerful computers in the network, and are critical to the functioning of the network. At first the server receives the data and then distributes them. The star topology is a suitable example of client-server architecture. In this type of networking, all the clients are busy at the time of data distribution by server. Advantages of Server-Based Network • Centralised user accounts, security, and access controls to simplify network administration. • More powerful equipment means more efficient access to network resources. • A single password for network login delivers access to all. • Server-based networking makes the most sense for networks with 10 or more users or any networks where resources are used heavily.
Oasis Radiant Computer Science, Book 10 24 Approved by Curriculum Development Centre Disadvantages of Server-Based Network • At worst, server failure leads to whole network failure. • Complex, special-purpose server software requires allocation of expert staff, which increases expenses. • Dedicated hardware (server) and special software (NOS) add to the cost. Centralised network architecture Centralised network architecture is a type of network where all users connect to a central server, which is the acting agent for all communications. This model enables the operation of all of a central server’s computing resources, administration and management. The central server, in turn, is responsible for delivering application logic, processing and providing computing resources. Advantages of Centralised network Provides high data security due to centralised control. Data processing in this system is consistent. Since this system uses less hardware, it reduces the cost. Disadvantages of Centralised network High data traffic can cause input-output blockage This system reduces the local accountability. On the Basis of Geographical Location We can allocate the computers on different locations when working with the computers networked environment. According to the placement distance of computers, we have three types of computer network. Local Area Network Networks used to interconnect computers in a single room, rooms within a building and buildings premises is called Local Area Network (LAN). LAN transmits data with a speed of several megabits per second (106 bits per second). The transmission medium is normally a coaxial cable. User User User User Server User User User User
Approved by Curriculum Development Centre 25 Oasis Radiant Computer Science, Book 10 LAN links computers, i.e., software and hardware, in the same area for the purpose of sharing information. Usually LAN links computers within a limited geographical area because a cable must connect them, which is quite expensive. People working in LAN get more capabilities in data processing, work processing and other information exchange compared to stand-alone computers. Because of this information exchange, most of the business and government organisations are using LAN. Characteristics of LAN • Every computer has the potential to communicate with any other computer of the network. • High degree of interconnection is there between computers. • Easy physical connection of computers features in a network. • Inexpensive medium of data transmission. • High data transmission rate. Advantages • The reliability of network is high because the failure of one computer in the
Oasis Radiant Computer Science, Book 10 26 Approved by Curriculum Development Centre network does not affect the functioning of other computers. • Addition of a new computer to network is easy. • High rate of data transmission is possible. • Other computers can share peripheral devices like magnetic disk and printer. Disadvantages • If the communication line fails, the entire network system breaks down. • User’s authority and identification are poor. Use of LAN Following are the major areas where LAN is normally used: • File transfers and access • Word and text processing • Electronic message handling • Remote database access • Personal computing MAN (Metropolitan Area Network) MAN is a high-speed network that can carry voice, data, and images up to 200Mbps or faster over distances of up to 75km. Based on the network architecture, the transmission speed can be higher for shorter distances. It is smaller than Wide Area Network but works in higher speed than WAN. It is the collection of individual network structures and the telecommunication system spreading throughout the metropolitan area. For example, TV channel network that provides the Internet and TV channel facilities to us. WAN (Wide Area Network) A communications network that connects geographically separated areas. In other words the term WAN (Wide area network) is used to describe a computer network spanning regional, national and global areas. It provides long-distance transmission of data, voice, image, and video information over a large geographical area in a country,
Approved by Curriculum Development Centre 27 Oasis Radiant Computer Science, Book 10 a continent or even worldwide. For example, for a large company the headquarters might be in Kathmandu and regional branches at Singapore, Mumbai and Lamjung Bhorletar. Here regional centres are connected to headquarters through WAN. The distance between computers connected to WAN is larger. Therefore the transmission medium used is normally telephone lines, microwaves and satellite links. Network Topology A network topology is the physical layout of configuration of computers, cables, and other components on a network. There are a number of different network topologies. The different types of network layouts are Bus topology, Star topology, Mesh topology, Ring topology, Hybrid topology and Wireless topology. The pattern of combination of computers for transferring data is called networking topology. It is a physical layout of the network’s computers, terminals, and links. These are Star, Ring, Bus and Mesh topologies. Star Topology A star topology is designed with each node (like workstations, printers, laptops, servers etc.) connected directly to a central device called a network switch. Each workstation has a cable that goes from its network card to a network switch. Most popular and widely used LAN technology Ethernet currently operates on Star Topology. Advantages • Easy to install. • No disruptions to the network when connecting or removing devices. • Easy to detect faults and to remove parts.
Oasis Radiant Computer Science, Book 10 28 Approved by Curriculum Development Centre Disadvantages • Requires more cable. • If the connecting network device (network switch) fails, nodes attached are disabled and cannot participate in network communication. • More expensive than linear bus topology because of the cost of the connecting devices (network switches). Ring Topology In a ring topology, all computers are connected via a cable that loops in a ring. A ring topology is a circle that has no start and no end. Terminators are not necessary in it. Signals travel in one direction on a ring while they pass from one computer to the next, with each computer regenerating the signal so that it may travel the distance required. Advantages • An orderly network where every device has access to the token and the opportunity to transmit. • Under heavy network load, it performs better than a star topology. • To manage the connectivity between the computers it doesn’t need network server. Disadvantages • Failure of one workstation will fail the entire network. • Moving, adding and change of devices can affect the entire network. • It is a very traditional system, so is difficult to maintain and use.
Approved by Curriculum Development Centre 29 Oasis Radiant Computer Science, Book 10 Bus Topology A bus topology consists of a main run of cable with a terminator at each end. All nodes like workstations, printers, laptops, servers etc., are connected to the linear cable. The terminator is used to absorb the signal when the signal reaches the end, preventing signal bounce. In bus topology, when a computer sends out a signal, the signal travels the cable length in both directions from the sending computer. When the signal reaches the end of the cable length, it bounces back and returns in the direction it came from. This is known as signal bounce. Signal bounce will create problem in the network, because if another signal is sent on the cable length at the same time, the two signals will collide. Advantages • Easy to connect a computer or peripheral to a linear bus. • Requires less cable length than a star topology. Disadvantages • Entire network shuts down if there is a break in the main cable. • Terminators are required at both ends of the backbone cable. • Difficult to identify the problem if the entire network shuts down. • Not meant to be used as a stand-alone solution.
Oasis Radiant Computer Science, Book 10 30 Approved by Curriculum Development Centre Tree Topology A tree topology combines characteristics of linear, bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs. Advantages • Point-to-point wiring for individual segments. • Supported by several hardware and software vendors. Disadvantages • Overall length of each segment is limited by the type of cabling used. • If the backbone line breaks, the entire segment goes down. • More difficult to configure and wire than other topologies. Mesh Topology Mesh Network is a network where all the nodes are connected to one another and is a complete network. In a Mesh Network every node is connected to other nodes on the network through hub. While the data is travelling on the Mesh Network it is automatically configured to reach the destination by taking the shortest route. Data travels from one node to another and then reaches the destination node in a Mesh Topology Network. Advantage • This type of network is very reliable as any line breakdown will affect the communication only between the connected computers.
Approved by Curriculum Development Centre 31 Oasis Radiant Computer Science, Book 10 • Each node of the network need not have individual routing capacity. • Communication is very fast between any two nodes. Disadvantages • It is a very expensive network topology. • It is complex in nature and difficult for maintenance and installation. • It is very difficult and costly to expand. Hybrid Topology Hybrid topology is a mixture of different topologies. Example is star-bus topology. Protocol A network protocol can be viewed as a common network communication standard, which is used to define a method of exchanging data over a computer network. Network protocols define rules and conventions for communication between different devices, participating in a computer network. Protocols are the sets of rules by which communication happens over a network. Protocols are responsible for enabling and controlling network communication. They set the rules for the representation of data, the signals used in communications, the detection of errors, and the authentication of computing devices on the network. To communicate between us, we have to speak a common language. Similarly to communicate between two computers we have to establish a common language type rules and regulations. These rules for communication are called Network Protocols. A protocol describes how a packet of information is organised and the rules it follows when travelling across the network. Types of Protocol According to the network structure and architecture to work we have different types of network protocols. These are summarised as below:
Oasis Radiant Computer Science, Book 10 32 Approved by Curriculum Development Centre TCP/IP (Transmission Control Protocol/Internet Protocol) TCP/IP is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). HTTP (Hypertext Transfer Protocol) HTTP is the set of rules for transferring files (text, graphic images, sound, video, and other multimedia files) on the World Wide Web. As soon as a Web user opens their Web browser, the user is indirectly making use of HTTP. HTTP is an application protocol that runs on top of the TCP/IP suite of protocols. FTP(File Transfer Protocol) FTP, better known as File Transfer Protocol, basically is applied to transfer data from one particular computer to another above a world-wide network. Usually, an FTP is a primarily applied protocol for exchanging data over a particular network which normally supports TCP/IP protocol. SMTP (Simple Mail Transfer Protocol) SMTP is a delivery protocol only. It cannot pull messages from a remote server on demand. Other protocols, such as the Post Office Protocol (POP) and the Internet Message Access Protocol (IMAP) are specifically designed for retrieving messages and managing mail boxes. However, SMTP has a feature to initiate mail queue processing on a remote server so that the requesting system may receive any messages destined for it. TELNET Telnet is a user command and an underlying TCP/IP protocol for accessing remote computers. Through Telnet, an administrator or another user can access someone else’s computer remotely. On the Web, HTTP and FTP protocols allow you to request specific files from remote computers, but not to actually be logged on as a user of that computer. With Telnet, you log on as a regular user with whatever privileges you may have been granted to the specific application and data on that computer. Internet and its services Definition Internet is defined as the International Network which is the network system of various networks. It exists in a global form. We can connect the internet on
Approved by Curriculum Development Centre 33 Oasis Radiant Computer Science, Book 10 the basis of standard rules, regulations and structure. The standard rules and regulations adapted to build the network structure are called protocols. Business Use of Internet Since internet has become a major part of the society and business sector, different institutions should use this application as a major tool to integrate with the supplier, customer and other business stakeholder. Here are some major application areas of internet in business and service sector. • It is applicable for advertisement of the institution using World Wide Web. • It is used for communication between different users and institutions using email, internet, etc. • It is used for entertainment. We can browse different web sites and communication system on internet for entertainment. • It is used to distribute information to the concerned people. • It is applicable for online news publishing and processing. • It makes using online job offer possible to recruit people. • It is applicable for research and development because we can download so much of related information and documents. • It makes it possible to promote online services and commerce called e-commerce. • It makes it possible to give online support and advices to the needy people. • It makes it possible to attend online classes for online education and training.
Oasis Radiant Computer Science, Book 10 34 Approved by Curriculum Development Centre Requirement to Connect Internet We know that the internet is a global networking system so a network structure is essential to connect us to the internet. Basically we need the following devices and system to connect to the network structure. 1. Computers: We need a working computer system or other internet access devices to connect to the internet. The devices are mobile set, laptop computer, PDA (Personal Digital Assistant), etc. 2. ISP (Internet Service Providers): ISP provides the user name and password for us to get access to the internet system. User should pay some amount to the ISP and get the access rights to the internet system 3. Signal Conversion Devices: We have to use signal conversion devices on the internet so that it is easy to convert analogue data to digital data and vice versa to process within the internet system. For example, Modem (Modulator and demodulator), Router, etc. Modem is a popular device that is used to modulate and demodulate the signals i.e. convert digital to analogue and analogue to digital. 4. Communication Medium: We have some connected path to transfer data from one location to another. These are called communication medium. We have two types of communication medium: Wired and Wireless. 5. Web Browser Software: We have to use web browsers such Internet Explorer, Mozilla, and Netscape Navigator. Advantages of Internet The internet provides many facilities to the people. The main advantages of internet are: 1. Sharing Information: We can share information with other people around the world. The scientists or researchers can interact with each other to share knowledge and to get guidance etc. Sharing information through internet is very easy, cheap and fast. 2. Collection of Information: A lot of information of different types is stored on the web server on the internet. It means that billions of websites contain different information in the form of text and pictures. You can easily collect information on every topic of the world. For this purpose, special websites,
Approved by Curriculum Development Centre 35 Oasis Radiant Computer Science, Book 10 called search engines are available on the internet. The most popular search engines of the early years were altavista.com, search.com, yahoo.com, ask. com. The scientists, writers, engineers and many other people use these search engines to collect latest information for different purposes. Usually, the information on the internet is free of cost. The information on the internet is available 24 hours a day. 3. News: You can get the latest news of the world on the internet. Most of the newspapers of the world are also available on the internet. News websites offer the latest news about the events happening in the world. These websites are periodically updated or they are immediately updated when any noteworthy event happens around the world. 4. Searching Jobs: You can search different types of jobs all over the world, Most of the organisations/departments around the world, advertise their vacant vacancies on the internet. Search engines are also used to search for jobs on the internet. You can apply for jobs online. 5. Advertisement: Today, most of the commercial organisations advertise their products through the internet. It is a very cheap and efficient way for advertising products. The products can be presented in attractive and beautiful packages to entice the people around the world. 6. Communication: You can communicate with others through internet around the world. You can talk while watching one another; as if you are talking with your friends in your drawing room. For this purpose, different services are provided on the internet such as: • Chatting • Video conferencing • E-mail • Internet telephony etc. 7. Entertainment: Internet also provides different type of entertainment to the people. You can play games with other people in any part of the world. Similarly, you can see movies, listen to music, etc. You can also make new friends on the internet for fun. 8. Online Education: Internet provides the facility to get online education. Many websites of different universities provide lectures and tutorials on
Oasis Radiant Computer Science, Book 10 36 Approved by Curriculum Development Centre different subjects or topics. You can also download these lectures or tutorials into your own computer. You can listen to these lectures repeatedly and get a lot of knowledge. It is very cheap and easy way to get education this way. 9. Online Results: Today, most of the universities and education boards provide results on the internet. The students can watch their results from any part of the country or world. 10. Online Airlines and Railway Schedules: Many airline companies and railways provide their schedules of flights and trains respectively on the internet. 11. Online Medical Advice: Many websites are also available on the internet for people to get information about different diseases. You can consult a panel of online doctors to get advice about any medical problem. In addition, a lot of material is also available on the internet for research in the medical field. 12. E-commerce: Process of buying and selling goods and services online specialty by using the internet is called e-commerce. It integrates communication system, security mechanism, online payment system, and third party to deliver goods and services to enable the e-commerce transactions. Basically, all the commercial transactions are processed on digital data on e-commerce. Now-a-days, we have a special type of e-commerce called mobile-commerce (m-commerce) which exists on the wireless communication network. It is possible to access the internet on our mobile phone and do the business. There are different types of e-commerce. According to the involvement of business partners, we have B2B (Business to business), B2C (Business to consumer), C2C (Consumer to consumer), etc. E-commerce has some merits over traditional commerce such fast processing, low cost transaction, global reach, no bargain, and opportunity to get new customers, etc. Besides these merits, it has some demerits such as chances of fraud, language problem, lack of infrastructure, no interpersonal relationship, and need of skilled users to operate it.
Approved by Curriculum Development Centre 37 Oasis Radiant Computer Science, Book 10 Disadvantages of Internet Although the internet has many advantages it also has some disadvantages. The main disadvantages are: 1. Viruses: Today, internet is the most popular source of spreading viruses. Most of the viruses transfer from one computer to another through e-mail or when information is downloaded on the internet. These viruses create different problems in your computer. For example, they can affect the performance of your computer and damage valuable data and software stored in your computer. 2. Security Problems: Valuable websites can be damaged by hackers and your valuable data may be deleted. Similarly, confidential data may be accessed by unauthorised persons. 3. Immorality: Some website contains immoral materials in the form of text, pictures or movies etc. These websites damage the character of new generation. 4. Filtration of Information: When a keyword is given to a search engine to search for information on a specific topic, a large number of related links are displayed. In this case, it becomes difficult to filter out the required information. 5. Accuracy of Information: A lot of information about a particular topic is stored on the websites. Some information may be incorrect or not authentic. So, it becomes difficult to select the correct information. Sometimes you may be confused. 6. Wastage of Time: A lot of time is wasted to collect the information on the internet. Some people waste a lot of time chatting or playing games. At home and office, most of the people use the internet without a positive purpose. 7. Language problems: Most of the information on the internet is available in English language. So, some people cannot avail the facility of internet. Basic Terms Web Site: The World Wide Web consists of files, called web pages, which contain information and links to resources throughout the internet. It is an electronic
Oasis Radiant Computer Science, Book 10 38 Approved by Curriculum Development Centre document written in computer languages such as hyper text mark up language (HTML). Web Site: It is a set of related web pages published by an organisation or individual. Normally it contains home page along with other additional web pages. It is addressed with a special location name that is called web site address on internet. Home page: It is the starting page or doorway to the web site like the table of contents of book. It gives details about pages linked inside the website. Sometimes, it is called an index page or host page that contains so many links to get access to the multiple pages. Browser: Web browser is a programme that accesses web pages and displays them on the computer screen. It is the basic software that is needed to find, retrieve, view and send information over the internet. Uniform Resource Locater (URL): Each web page has a unique address called a Uniform Resources Locater (URL) that identifies its location on the internet. Basic format of URL consists of four parts: Protocol, host computer, server or domain and file name. http://www.xyz.com/introduction.html Protocol: http (Hyper Text Transfer Protocol) Host computer: www (Word Wide Web) Domain Name: xyz Domain Type: com (Company) File Name: introduction.html Hyper Text: It refers to the text which connects to other documents. These texts are known as hyper text link, hyperlink or simply link. It is used to jump to another page or another part of the working page. ISP (Internet Service Provider): It is an organisation that provides the internet connection to different users. They charge some amount to the user to provide the internet service. They provide user name and password to access to the internet system. In Nepal we have some ISPs. Popular ISPs are Mercantile Office System, and Worldlink Communication. Download and Upload: Download refers to the activities of copying a document, programme or other data from internet or other network structure to one’s own computer and working window. It is the “Pulling” of information from server to working window of the system.
Approved by Curriculum Development Centre 39 Oasis Radiant Computer Science, Book 10 Upload is the process to place document, data or other multimedia data on internet server. To upload the information we need web space and the standard document compatible to display on internet. Email: Electronic mail is a fast, easy and cheap way to communicate with others using the internet system. It is the basic service of internet. Email has a mail box address to which messages are sent and these are accessed from any part of the world at any time. There are two types of emails. These are web mail and SMTP (Simple Mail Transfer Protocol) mail. Web mails exist on the internet page like hotmail and yahoo mail. SMTP mail is available on the outlook express, available on windows system. We can compare the email and general post mail as below: E-mail Postal Mail • Very fast medium • Very slow in comparison with e-mail • Cheap • Expensive • Easy to send voice, images and other types of data • Difficulties while sending other types of data • Same message can be sent to several recipients at the same time. • Same message has to be sent in different envelopes. • Recipients can receive message from anywhere, any time. • Recipients can receive message only at the marked address. Email Address An email address is required to send and receive email. Email addresses are different from “mail” addresses. They usually consist of three parts: a user name, an “at” symbol (@), and a domain name. [email protected] 1. User name: sea_adhikari located to the left of the @ symbol, a user name identifies your account on the email server that handles the email. 2. @: means “at” and separates your account name and the name of the mail server. 3. Domain Name: hotmail.com. The domain name usually consists of two pieces of identifying information. The first piece is the name of the email
Oasis Radiant Computer Science, Book 10 40 Approved by Curriculum Development Centre server and is located to the right of the @ symbol like hotmail. The second piece, usually a three-letter extension, indicates the top-level domain. They are separated by periods, called “dots”, like .com. Domains Top-level domains may help you figure out the type of organisation the recipient is associated with. See the chart below. Extension Meaning .com A company or business .org A non-profit or not-for-profit institution .gov Governmental agency .mil Military .edu Educational institution .net ISP or Network Provider If there is a two-letter extension, it is usually a country code. For example, Malaysia uses “.my” Types of Email Accounts Email is one of the most used features of the web. With this technology you can not only send text messages but also digital files such as images, audio, video, etc. attached with the message. There is little or no cost in sending an email and the best part - it’s almost instantaneous. There are different types of email accounts. 1. Web based email accounts: I’m sure all of you are aware of Hotmail, Gmail or Yahoo! Mail. All these services provide both web based free email accounts and paid versions of the same with extra features. These are called web based email accounts. 2. Email accounts provided by the ISP: ISPs generally provide an email account for free with the internet connection. However, there is one major drawback in having your ISP account as your primary email address for online correspondence. If you change your service provider or shift to a new location where your old ISP has no service, you might lose the email address. 3. Web site email accounts: Do you have your own web site? Depending on your hosting package, you can create email accounts on the web site for yourself or your staff. Most web hosting companies let you access emails.
Approved by Curriculum Development Centre 41 Oasis Radiant Computer Science, Book 10 4. Email account from your company: If you work in a medium-sized or a large company they would probably have their own email servers. Generally, you get your own email address a few days after joining the company. Advantages of Emails • The delivery of message is very fast and sometimes almost instantaneous. It is similar for all locations, from overseas to the next door. • The cost of emailing is almost free. But it involves negligible amount for communication like phone and for ISP (Internet Service Provider). • Multiple copies of the same message can be sent to different people. • Pictures, files and other multimedia data can be attached with email. • It helps to enhance the communication system of user. Disadvantages of Emails • Although e-mail is delivered on time receivers may not read their mails on time. • User should stay online to read and write mails. • The system is totally based on the internet or other networked based system. So failure of network may discontinue the email services. • It is a knowledge-based application so all users are not able to use this system. • Sometimes some unnecessary mails called junk mails may mislead the user. Points to remember • Sending and receiving information from one location to another location is called data communication. • There are five components of data communication. These are: message, sender, receiver, medium and protocol. • Data transmission mode refers to the direction of data communication. These are simplex and duplex. • Simplex is one-way transmission and duplex is two-way transmission. • Full duplex uses the same path for sending and receiving message at the same time and half duplex uses the same path but sends and receives message in different times. • Data communication speed can be measured in terms of megabytes per second (MBPS), gigabytes per second (GBPS). • Connecting multiple computers to share the resources is called computer networking.
Oasis Radiant Computer Science, Book 10 42 Approved by Curriculum Development Centre • To connect a computer network, we need a computer system, connecting medium, connecting devices and the software. • The path to connect multiple computers in a network or other communication system is called communication channel or media. • We have two types of communication channel. These are guided and unguided channels. • Guided channels are cables like twisted pair, co-axial and fibre optic and unguided channels are microwave, satellite, Bluetooth and Infrared. • Basically, we can classify the network into two types. On the basis of architecture, we have peer-to-peer and client-server network types and on the basis of distance, we have LAN, MAN and WAN. • The technique of data transmission from node to node in which each node behaves like a server or client is called peer-to-peer network. • The network structure in which at least one computer works like a host or server computer which controls all other working client computers is called client-server network. • Network connection style or configuration is called topology; we have mesh, bus, star and ring topologies. • A big network that integrates various computers from different parts of the world to share the resources globally is called internet. • Collection of web pages addressed with a unique location is called website. • Internet page that consists of different information in the form of text, audio, video, and animation is called web page. • Main index page that contains the links to multiple web pages is homepage. • Internet service provider (ISP) is an organisation that provides internet services to users. • Process to place information to the internet server is called upload and process to copy information from server and display on our working window is called download. • We can use internet in different sectors like chatting, telephone network, emails, website, e-commerce. • Selling and buying the goods and services using internet in digital form is called the e-commerce.
Approved by Curriculum Development Centre 43 Oasis Radiant Computer Science, Book 10 Exercises 1. Answer the following questions: a. What is data communication? Write its components. b. Define the terms simplex and duplex, with examples. c. What is bandwidth? Write its types. d. What is computer networking? Explain its advantages and disadvantages. e. List the devices required to connect computers for networking and explain them. f. What is a communication channel? Explain its types in brief. g. List some guided communication media and explain them. h. What are unguided communication media? Explain their types. i. What is a network topology? Explain its types with merits and demerits. j. What is LAN? Write its features. k. What is MAN? Explain. l. What is WAN? Write its use. m. What is a peer-to-peer network? Write its advantages and disadvantages. n. What is a client-server network? Write its features. o. What is network topology? Write its use. p. What is a modem? Write its use. q. What NIC? Write its functions. r. What is a twisted-pair cable? Explain its types. s. What is internet? List any two services that internet provides. t. Write any four advantages of email over postal mail. u. What is IRC? List any two advantages of email. v. Explain the importance of internet in business. w. Explain briefly about e-commerce. Give any two examples of websites which perform e-commerce. x. Write some advantages and disadvantages of internet.
Oasis Radiant Computer Science, Book 10 44 Approved by Curriculum Development Centre y. Define web browser. List some popular web browsers. z. What is downloading and uploading? aa. What is a website? ab. What is a URL? ac. What is a protocol? Write the features of FTP. ad. What is email? Explain its advantages and disadvantages. ae. Write the use of internet in education sector. 2. Write short notes on: a. Duplex i. Coaxial cable b. Fibre optic cable j. Satellite transmission c. Telnet k. Hub d. Router l. Gateway e. Protocol m. Networking software f. Downloading and uploading n. URL g. E-commerce o. News group h. Email 3. Write full forms of: a. KBPS b. GBPS c. MBPS d. LAN e. WAN f. MAN g. NIC h. Modem i. UTP j. STP k. TCP l. IP m. HTTP n. FTP o. URL p. SMTP q. POP s. Telnet t. UDP u. DNS v. NNTP y. IRC z. WWW aa. CDMA ab. ADSL ac. BLOG ad. DNS ae. W3C af HTTP ag. WiFi 4. Fill in the blanks. a. Communication means_____ and___________ information. b. Standard rules and regulations are called___________ . c. Transmission of data using the same path at the same time is__ .
Approved by Curriculum Development Centre 45 Oasis Radiant Computer Science, Book 10 d. Broadcasting of TV to transmit the data is example of ____ transmission. e. Measurement of data that transmits in a given time is defined as _____ ___. f. The device that converts digital data to analogue and again analogue to digital is called__________ . g. ___________ communication channel that transfers data with the help of light. h. Coaxial cables transfer data in the form of_____________ . i. Channels that can transfer multiple signals at a very high speed are called ________ channels. j. Protocol defines the _________ structure and ______ for network k. Global network connection is called ______________. l. Process to copy information from internet to working system is called ___________ . m. Process to place information on internet is called__________ . n. Software system that helps to display web pages is called____ . o. Modem isconversion device. p. Company that provides internet service to the users is called -- 5. State True and False. a. Modem converts signals from analogue to digital and vice-versa. b. Fibre optic cable has very high speed of data transmission. c. STP is more secured than UTP. d. Peer-to-peer network is suitable for large network structure. e. Local area network exists in global form. f. Broadband channel can transmit multiple signals with very high speed. g. Twisted pair cable can transfer data in terms of gigabyte per second. h. Mesh topology is costlier than star topology. i. Simple Mail Transfer Protocol (SMTP) is related to internet browsing. j. HTTP is Hyper Text Transmission Protocol. k. Internet deals with the global network connection by collecting so many local networks. l. Internet is international network which distributes information globally. m. E-mail system helps to send and receive electronic mails.
Oasis Radiant Computer Science, Book 10 46 Approved by Curriculum Development Centre n. Selling and buying goods and services using internet is called electronic commerce. o. It is not possible to use internet as communication system. p. Webpage is the collection of websites. q. Internet service providers give internet service. r. Dialup connection is faster than broadband connection of internet. s. Signal conversion devices convert the analogue to digital and digital to analogue signals. t. Web browser is software that displays websites. u. File transfer protocol helps to transfer the file. v. Pulling information from the internet is called downloading. w. Broadband technology transfers multiple signals with high speed. 6. Match the following: i. Group A Group B UTP BNC Network architecture layout of network Co-axial cable blue print of network Topology standard of network RJ - 45 ii. Group A Group B SMTP to upload and download file HTTP to access web sites FTP Internet telephony VOIP Remote Login Used in Email Service iii. Group A Group B First web browser Dr. Tim Berners Lee WWW NCSA Mosaic E-commerce Search engine Alta Vista Online shopping Opera
Approved by Curriculum Development Centre 47 Oasis Radiant Computer Science, Book 10 i. Group A Group B Internet Service Company Collection of Web pages Online shop ping ISP Web site The first Page of Internet Home Page E-commerce Internet 7. Select the correct answer. a. Which is not a network hardware component? i) HUB ii) Repeater iii) Router iv) Windows NT b. In which communication media does data travel in the form of light signal? i) Telephone wire ii) Fibre optic iii) Coaxial cable iv) Twisted pair cable c. Which is not a protocol? i) TCP/IP ii) IPX/SPX iii) NETBIOS/NETBUI iv) Client d. Which of the following is the basic internet protocol? i) HTTP ii) POP iii) TCP/IP iv) None of the above e. WLAN can be set up by using………… i) Coaxial cable ii) UTP cable ii) Bluetooth iv) All of the above f. The hub or switch is used in ……… topology. i) Bus ii) Star iii) Ring iv) All of the above g. In which of the following transmission media, transmission and receiving nodes need to be in line of sight? i) Twisted pair cable ii) Microwave iii) Bluetooth iv) Optical fibre h. In which communication media data transfer speed is high? i) Twisted pair ii) Coaxial cable iii) Fibre optics iv) Microwave i. A device with multiple points which acts as central location for different computers and other devices placed in a network
Oasis Radiant Computer Science, Book 10 48 Approved by Curriculum Development Centre i) Connector ii) MODEM iii) HUB iv) NIC j. Which is not an unguided media? i) Fibre optic ii) Microwave iii) Infrared iv) Radio wave k. In http://www.abc.com, the com is : i. URL ii. Host name iii. Domain type iv. Path l. A special computer in the internet that contains hyperlinked documents is known as……… ii. Website ii. Database server iii. Web server iv. Client server m. Which of the following is not a search engine? i. Google ii. Yahoo iii. Bing iv. Mozilla Firefox n. Which of the following is correct email id : o. Which is online business through internet? i. E-Commerce ii. E-Mail iii. MODEM iv. FAQ p. Which is a web browser software? ii. Window 2007 ii. Internet explorer. iii. Window NT iv. All of the above. h. Which is not related to internet? i. ISP ii. TCP/IP iii. WWW iv. UPS i. Which is the internet service? i. IRC ii. Telnet iii. E–mail iv. All of the above j. In the URL http://www.nepalnews.com, http is a i. Protocol ii. Webpage iii. Domain iv. Sub domain 7. Give the technical term: a. A hardware device that converts digital signal to analogue and vice versa. b. Set of rules and procedures that is followed by nodes in network communication.
Approved by Curriculum Development Centre 49 Oasis Radiant Computer Science, Book 10 c. A hardware device that connects different networks having dissimilar protocol. d. The cabling structure of the nodes in a network. e. A guided transmission media through which data signals flow in the form of light signal. f. A hardware device that receives weak signal and amplifies it. g. Physical layout of LAN. h. Number of bits that can be transferred per second over a given transmission medium. i. A main computer in the computer network. j. Two-way communication mode. a. Buying and selling products and services online. b. Real time visual communication service of internet. c. A service of the internet that allows a user to connect a remote computer. d. A service of the internet that allows a user to search information from web servers if the URL is unknown. e. A service of the internet that allows a user to post questions for discussion. f. An internet tool that helps to upload/download the file. g. A person who steals or destroys other’s data, information and programme. h. A company that provides internet services. i. An application which allows users to view documents on the WWW. j. The worldwide network of computer. 8. Class Activities and Project Works. a. List the network devices used in your computer lab. b. List any ten protocols and give their functions on network. c. Analyse and draw a typical network diagram of your lab network structure. d. Compare between different topologies in terms of connection style, cost, speed, expansion of network, and maintenance. e. Collect some articles from daily newspapers and prepare a project report about use and application of internet in banking sector. f. Find out the internet connection technology in your school. List its advantages and disadvantages over other technologies. g. Do you know about social network? Give an example. Why and how do you use such a network?
Oasis Radiant Computer Science, Book 10 50 Approved by Curriculum Development Centre Chapter 2 Ethical and Social Issues in ICT ffl Digital Citizenship ffl Digital Footprint ffl The IT Policy 2072 ffl The Electronic Transaction Act ffl Opportunities and Threats in Social Media THIS CHAPTER COVERS :