Computer ...........Vacatiion homework!!!!!!!! Chapter 1 Networking and Telecommunication Networking A group of interconnected computers including hardware and software used to communicate and provide users with the access to shared resources (hardware and software); is called networking. Merits of networking 1. Hardware and software can be shared using networking terminal. 2. Networking computers can update records among them. 3. It save time and money and increases working efficiency and give results promptly. 4. It allows electronic mail to be sent among the user. 5. Data can be safe under networking computers. Demerits of networking 1. It is expensive to make networking as it needs manpower devices. 2. Sometimes it is difficult to solve problems because of cabling system 3. Users become dependent on server. 4. It is difficult to make system secure from hackers 5. Virus may be spread widely 6. Data and software may be deleted too. Types of network 1) Lan: A group of computers that connects computer that are closed to each other usually in the same building linked by a cable. Merits 1. It is cheaper system as no charge should be paid . 2. It does not need highly qualified persons. Demerits 1. It is useful for small area only 2. Office automation system looks untidy as there will be more cabling. Features 1. It is used for small area 2. It is especially useful for a office automation with single management. 2) Man: It is a networking system covering a certain geographical area. Under this system computers are connected through cabling system or radio wave system. It is useful for networking computer for small area. Merits 1. It covers the area of a city. 2. It is larger than LAN. Demerits 1. They only cover an area of cities. 2. It is expensive system as charge should be paid to install and get the service. 3) Wan A networking in which computers are connected to each other over a long distance using telephone line or satellite connection. Under this system information can be shared worldwide through satellite. Services which under Wan system 1. International banking 2. Net 3. E-mail 4. Health net 5. Chatting 6. International money transfer Merits 1. It covers wide area. Data can be transferred and access to any computer in the world which are connected in wan 2. It saves money and time as many jobs can be done from single computers. 3. It does not need cabling .so, office automation looks tidy. Demerits 1. It is expensive method charge should be paid to install and get the service. 2. It needs highly qualified persons. Topology LAN (physical layout of lan) The pattern in which computers over interconnected is called network topology or LAN topology. Among them 1. Bus topology 2. Ring topology 3. Star topology 4. Mesh topology 1. Bus topology: It is a pattern of connecting computers through a common back bone cable. Merits 1. It is not expensive system as single cable is used. 2. It doesn’t need highly qualified person to install. 3. It can be done among many computers. Demerits 1. It is not useful for high load environment. 2. Difficult to solve problem due to cabling system. 2. Ring topology It is a pattern of connecting in a closeed loop by single communication cable network cable is connected to all computers. Merits 1. It can be used in highly load environment 2. Data can be transferred at high speed. 3. Less problem is faced. Demerits 1. It is expensive in comparison to other types. 2. Highly person is needed. 3. Star topology It is a pattern of connecting every computer by ether net cables to central controller(hub). Merits 1. It is easy to install new terminal without disturbing the network system. 2. Work station are not effected some cables are failed. Demerits 1. It is not easy to configure the system. 2. It needs more cabling hub.so it is expensive. System of LAN topology There are two ways of LAN system:- 1. Client server network It is the way of the LAN system in which file server and work station. File server include operating system necessary software. File server is high capacity, high speed computer. Under this software work station on access the server nodes work under instruction of file server. Operating system to client server are LINUX, UNIX, WINDOS NT etc. Merits 1. Network can be expanded to any size. 2. Security system is effective . 3. Software installing only in server can serve to all client. Demerits 1. It needs trained manpower to handle this system. 2. It is expensive system as server is needed. 3. Terminal has to depend on server. 2. Peer to peer network It is way of LAN system under which every terminal possesses hardware and software. It does not need server. All terminal work equally and they are independent. Merits 1. It is suitable for small area. 2. It is less expensive as server and trained manpower is not necessary. 3. Terminals do not depend upon server. Demerits 1. Security facility is limit. 2. It is useful for small area only. Networking connecting devices Different devices are necessary for networking, which are:- 1. Computer It is an electric device. . Channel It is medium through which data are transferred. It may be wired or wireless. Channel may be cables, microwave, radio wave, satellite, etc. 3. NIC It is a card which helps to connect in network system. It is necessary for LAN. 4. Hub It is a connecting device containing multiple ports for connecting the computers in network. It remains between file server and terminal. 5. Bridge It is a device which helps to connect same type of computer system in network. Using bridge we can connect same type of computers in network. 6. Gateway It is a same to bridge but it can connect different types of computers. 7. Router It is a device which helps to transfer data between different types of system. 8. Repeater It receives data and sends forward. 9. Connecting device It is small connecting device used to connect cable into NIC. Communication media (channel) The way through which datas are transferred from one computer to another computer is known as communication media or channel. It may be of two types: 1. Wired 2. Wireless Wired communication If in networking system data are transferred through cable, is called wired communication. For the purpose of data transfer, different types of cables are used, like: A. Twisted pair cable i.UTP – (Simple plastic casing, low cost, easier to work, used for LAN) (Not high bandwidth, not good protection from external interference) ii. STP- (Covering with woven copper, protected from external interference, more bandwidth, efficiency) (Difficult to install, expensive) B.co-axial cable Co-axial cable is used in communication network that requires many simultaneous communication links. There are two types of co-axial cable. They are: 1. Thinnest 2. Thickest C. Fibre-optic cable Fibre optic cable is made up of light conducting glass or plastic and surrounded by glass. Merits 1. It can transfer more data. 2. It is less susceptible to interference. 3. Digital data’s can be transferred. Demerits 1. It is expensive. 2. It is more fragile. 3. It is difficult to split in need and bend. Wireless communication Under this system, data are transfer from one location without the use of interconnecting cables. Under this data are transferred with the help of radio wave, satellite, microwave, etc. Techniques for wireless communication 1) Microwave i. Data are transferred straight. ii. Antennas are used. iii. Economy, high speed, easy to transfer data. 2) Radio wave - Types of modulation AM, PM, & FM. 3) Satellite 1. Satellite is used for long distance transfer purpose. 2. Suitable for transferring text, data, sound and pictures. 3. Cheap MODEM It is a device which allows computer to transfer information from one computer to another over a telephone lines. It translate digital signal to analog and analog to digital. It can be classified as external and internal. External modem is kept outside the CPU and internal is kept inside the CPU. Bandwidth The amount of data that can be transmitted in a fixed time period is called bandwidth. The amount of data that can be sent over a line depends upon bandwidth. Bandwidth of digital device is measured in BPS and bandwidth of analog device is measured in Hertz or Cycle per Second. Data communication The process of transferring data from one computer to another is called data communication. E-mail Sending letter, picture, video, etc with the help of computer is called e-mail. E-banking Process of data banking transactions of computer. E - Shopping Buying and selling goods with the help of computer. Protocol Rules which are necessary to help communication and understand communication data of each other is called protocol. It is complete set of rule and standard that allows different device to make conversation. It is a software which should be installed on network computer. Some protocols are TCP/IP, IPX/SPX, SMTP, POP, etc. 1. What do mean by communication? Communication refers to exchange of idea and information between or among the person in different places using various means such as phone, radio wave, etc. 2. What is Tele-communication? It is a kind of contact using various communication devices. In other terms, it is the process of sending and receiving message through phone line using computer. 3. What are the modes of data transmission? Explain in short. There are two types of mode of data transmission. They are: i. Simplex communication: The mode of communication where there is only one way communication i.e, receiver cannot respond is regarded as simples communication such as: broadcasting from radios, newspaper, TV, etc. ii. Duplex communication The mode of communication where there is two way communication i.e., receiver can respond as well regarded as duplex communication. Types of duplex communication a. Half duplex: In this mode either sender or receiver can transmit message. E.g.: communication set of policeman b. Full duplex: In this mode of communication both the parties can make communication. e.g.: telephone service, mobile phone, etc. 4. Define modulator and demodulator Modulator is used to translate the digital signal of a computer to analog signals, which are then transmitted across the standard telephone line. Demodulator is used to translate the analogs into digital signal for the computer. 5. File server and terminal. Fileserver is the main computer having high capacity and server software and hardware to another computer. Terminals are the computer which are used as workstation and receives the software from server. 6. The internet is the main sources of computer virus. Justify it. As there is no any authority body to control the internet, anyone can add virus along with the data and information in their website and many computers will be affected by virus at a time. So internet is regarded as the main source of computer virus. 7. What are the aims of formulating cyber law in Nepal? The main aims of formulating cyber law in Nepal are:- 1. To legalize electronic transaction. 2. To stop cyber crime 3. To punish a person who does criminal activities through electronic means especially computer. 8. What is non- dedicated server? Non-dedicated server is the file server which can be used simultaneously as a workstation. 9. What is dedicated server? It is the single computer in a network reserved for serving the needs of networking. 10. Computer network makes the world small place. Justify this statement. Video conference allows people to communicate with each other looking their facts and it seems they are sitting very near to each other. Similarly chatting can be done online and it seems they are very near and various messages, pictures, audios, videos can be transferred all over the world within fraction of second. Hence world has become a small place to explore due to the advancement computer networking. 11. What is cybercrime? The criminal activities like stealing of information, accessing other data or information illegally, transferring of money without the knowledge of owner, copying and distributing software illegally or many other intentional activities that harm computer system and other properties, is known as cybercrime. Submitted By: Submitted To: AnIsh Harihar Sir
Posted on: Fri, 31 Jan 2014 12:31:12 +0000
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