Communication and Network conceptsVery Short Answer Questions:

1. Define a Network. What is its need?A network is an “interconnected collection of autonomous computers’.With the help of the Network on can satisfies the below given needs:1)Resource Sharing .2) Reliability.3)Cost Factor4) Communication medium.

2.Write two Advantages and Disadvantages of Network.Advantages:-Share Resources such as printers, modems, scanners, etc.-Improve communications. Messages can be sent. E.g Internet Email.Disadvantages:-If software and files are held centrally. It may be impossible to carry out any work. If the central server fails.-File Security is more important especially if connected to WANs. E.g. protection from viruses.

3.What is ARPANet? What is NSFNet?ARPANet:Advanced Research Project Agency (ARPAnet) is a project started by U.S. Department of Defence in 1969 the main objective of the project is to connect computers at U.S defence & different universities.NSFNet:National Science Foundation(NSFNet) is a federal agency started in mid 80’s the main objective is to provide a high-capacity network and to be strictly used for academic and engineering researches.

4.What do you understand by InterSpace?InterSpace is a client/server software program that allows multiple users to communicate online with real time audio, video and text chat in 3D-Environments.

5.Name two switching circuits and explain any one.Switching techniques are used for transmitting data across networks.When two computers communicates over network different types of switching techniques are used. These are:1)Circuit Switching 2) Message Switching 3) Packet Switching.Circuit Switching: In this technique, first the complete physical connection between two computers is established and then data are transmitted from the source computer to destination computer. The important property of this switching technique is to setup and end-to-end path (Connection) between computer before any data can be sent.

6.What is communication channel? Name the basic types of communication channels available.Communication channel is the medium used to carry information or data from one point to another.Some of them are:Guided Media: Twisted Pair Cable, Coaxial Cable, Optical Fibers.UnGuided Media:Micro Waves, Radio Waves, Satellite.

7.Define baud, bps and Bps. How are these interlinked.Baud: It is the unit of measurement for the information carrying capacity of a communication channel.bps: bits per second, It is generally used to measure the speed of information.Bps: Bytes per second, It is also used to measure the speed of information.The data transfer rate i.e. amount of data transferred per second by communication channel is measured in bps, Bps or baud.8. What are various types of Networks?Various types of networks are:Local Area Networks( LANs)Metropolitan Area Networks (MANs)Wide Area Networks (WANs)9. What is the difference between MAN and WAN?Metropolitan Area Networks (MANs) are the networks spread over a city. For example, cable TV networks.While,Wide Area Networks (WANs) are the networks spread across countries. For example, Internet.10. What is meant by topology? Name some popular topologies.Topology:The pattern of interconnection of nodes in a network is called the topology.Some of the popular topologies are:Star topology, Bus topology, Ring or circular topology, Tree topology, Graph topology, Mesh topology.11. What are the factors that must be considered before making a choice for the topology?There are a number of factors to be considered in making a choice for the topology, the most important of which are:-Cost.-Reliability. -Flexibility.12. What are the similarities and differences between bus and tree topologies?Similarities:Transmission in both the topologies takes place in the same way. In both cases, there is no need to remove packets from the medium because when a signal reaches the end of the medium, it is absorbed by the terminators.Differences:In bus topology, the shape of the network is linear.While,In tree topology, the shape of the network is like inverted tree.13. What are the limitations of star topology?Some of the limitations of star topology are:-It is difficult to expand.-Long cable length.-Central node dependency. If the central node in a network fails, the entire network is inoperable.14. When do you think, ring topology becomes the best choice for the network?If one wants to increase network reliability and is planning to install fiber optics as a transmission medium, then in my view ring topology is the best choice.

15. Write the two advantages and two disadvantages of Bus topology in network.Advantages:-Short cable length and simple wiring layout.-Easy to expand the network.Disadvantages:-Fault diagnosis is difficult.-Nodes must be intelligent.-Fault isolation is difficult.16. Briefly mention two advantages and two disadvantages of Star topology in network.Advantages:-Centralize control.-One device per connection.Disadvantages:-Long cable length.-Difficult to expand the network.17. Give two advantages and two disadvantages of tree topology in network.Advantages:--Answer to be found from the internet. (Pending)19. Write two advantages and disadvantages of Optical fibers.Advantages:-It is immune to electrical and magnetic interference.-It guarantees secure transmission and has a very high transmission capacity.Disadvantages:-Installation problem. It’s difficult to install.-Connection losses are common problem.-They are the most expensive of all the cables.

19. Write two advantages and disadvantages of Satellites.Advantages:-The area coverage through satellite transmission is quite large.-The laying and maintenance of intercontinental cable is difficult and expensive and this is where the satellite proves to be the best alternative.Disadvantages:-Over-crowding of available bandwidths due to low antenna gains.-Technological limitations preventing the installation of large, high gain antennas on the satellite platform.20. Write two advantages and disadvantages of Microwaves.Advantages:-It offers freedom from land acquisition rights that are required for laying, repairing the cables.-It offers ease of communication over difficult terrain.Disadvantages:-Microwave communication is an insecure communication.-Microwave propagation is susceptible to weather effects like rains, thunder storms etc.21. Write two disadvantages of twisted pair cables.Disadvantages:-Because of high attenuation, it is incapable of carrying a signal over long distances without the use of repeaters.-It’s low bandwidth capabilities make it unsuitable for broadband applications.

22. What is a modem? Name two categories of modems.A Modem is a computer device that allows us to connect and communicate with other computers via telephone lines.Modem comes into two categories:1- Internal modems.2- External modems.23. Define the following:(i) RJ-45 (ii) Ethernet (iii) Ethernet card (iv) hub (v) switch.

(i) RJ-45Registered Jack-45 (RJ-45) is an eight wire connector, which is commonly used to connect computers on the local are networks.(ii) EthernetEthernet is a LAN architecture developed by Xerox Corp along with DEC and Intel. Ethernet uses either a bus or star topology and supports data transfer rates up to 10 Mbps.(iii) Ethernet cardThe computers that are part of Ethernet, have to install a special card called Ethernet card. Ethernet card contains connections for either coaxial or twisted pair cables or both. If it is designed for coaxial cable the connection will be BNC. If it is designed for twisted pair it will have a RJ-45 connection. Some Ethernet card also contains an AUI connector.(iv) HubA hub is a hardware device used to connect several computers together. Hubs comes into two types: Active hub and Passive hub. Hub usually can support 8,12, or 24 RJ-45 ports.(v) SwitchA switch is a device that is used to segment networks into different subnetworks called subnets or LAN segments. A switch is responsible for filtering data over network and it supports any packet protocol.23. Define the following:(i) Protocol (ii) Host (iii) Repeater (iv) Bridge (v) Router (vi) Gateway.(i) ProtocolA protocol is a set of rules that two or more machines must follow to exchange the information.(ii) Host: A network host is a computer connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network. A network host is a network node that is assigned a network layer host address.(iii) RepeaterA Repeater is a network device that amplifies a signal being transmitted on the network. It is used in long distance network lines.(iv) BridgeA Bridge is a network device that establishes an intelligent connection between two local networks with the same standard but with different types of cables.(v) RouterA Router is a network device that is used to separate different segments in a network to improve performance and reliability. A router works like a bridge but can handle different protocols.(vi) GatewayA Gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external network with completely different structures.24. What is remote login? What is Telnet?The process of login into another computer of a network is called remote login. Once we login we can work on that system, just as we are sitting just next to it.Telnet:Telnet is a utility program that lets us log on to remote computer system.

25. Briefly explain file transfer protocol.One of the original services on the internet which was designed to allow for transferring files from one system to another. Files of any type can be transferred over the internet via FTP. 26. What is Internet? What is E-mail?Internet:Internet is a world wide network of computer network.E-mail:Electronic Mail (E-mail) is sending and receiving messages by computer over network.27. What are the advantages of E-mail? What are the disadvantages of E-mail?Advantages:-Speed. Electronic mail can be delivered almost as fast as the wire can carry it.-Low cost. A three page letter can cost about Rs.100 to fax. The same letter can be sent by e-mail for the cost of one local call.Disadvantages:-Hardware requirement, you have to be at a computer to read or print e-mail.-Impermanent. Your sent mail message may be altered by the mail servers.28. What is the structure of an E-mail message?E-mail message consists of three parts, the header, the body and the signature. The header at the top of the message, the body is the actual message, the signature comes at the end.Some common header lines includes:To:_____________Subject:__________Cc:______________Bcc:______________29. What is HTML? Where it is used?HyperText Markup Language (HTML) is a document-layout and hyperlink specification language. It is used for creating web document.30. What is URL? What is WWW?URL:Uniform Resource Locator specifies the distinct address for each resource on the internet.For e.g: http://cbse.nic.in/WWW:World Wide Web is a set of protocols that allows us to access any document on the net through a naming system based on URLs.31. What is protocol? Name some commonly used protocols.A protocol is a set of rules that two or more machines must follow to exchange the information.Some of the commonly used protocols are:-HTTP:Hyper Text Transfer Protocol.-FTP: File Transfer Protocol-TCP/IP: Transmission Control Protocol/ Internet Protocol.32. What is TCP/IP? What is HTTP?TCP:Transmission Control Protocol/ Internet Protocol is a network layered protocol generally used in Internet for sending and receiving information. TCP is responsible for making sure that the data grams get through the other end. It keeps track of what is send and retransmits anything that did not get through.HTTP:HyperText Transfer Protocol is an application-level protocol which is used by web browsers and web servers to communicate between them.

33. Define mobile communication and wireless communication.Mobile communication:Mobile communication means that the computing device is not continuously connected to the base or central network.Wireless communication:Wireless communication is simply data communication without a physical connection like cables.34. Define GSM, CDMA, WLL.GSM:GSM is short for Global System for Mobile communications; it is a leading digital cellular system. GSM uses narrowband TDMA which allows eight simultaneous calls on the same radio frequency.CDMA:CDMA is short for Code-Division Multiple Access, a digital cellular technology that uses spread- spectrum techniques.WLL:WLL is short for Wireless Local Loop is a system that connects subscribers to the public switched telephone network using radio signals as a substitute for other connecting media.35. Define the following: (i)3G (ii) EDGE (iii) SMS (iv) TDMA.3G3G is a specification for the third generation of mobile communications technology which offers broadband packet-based transmission of text, voice, video and multimedia data rates up to and possibly higher than 2Mbps, offering a services to mobile computer and phone users.EDGE:Enhanced Data rates for Global Evolution is a radio based high-speed mobile data standard which allows data transmission speeds of 384 kbps. EDGE was formerly called GSM384.SMS:Short Message Service (SMS) is the transmission of short messages to and from the mobile phone, fax machine and/or IP address.TDMA:Short for Time Division Multiple Access, a technology for delivering digital wireless service using time-division multiplexing (TDM). TDMA works by dividing a radio frequency into time slots and then allocating slots to multiple calls. In this way, a single frequency can support multiple, simultaneous data channels.36. What is Voice-Mail? What is Chatting?Voice-Mail:The voice-mail refers to e-mail systems that support audio. Users can leave spoken messages for one another and listen to the messages by executing the appropriate command in the e-mail system.Chatting:Online textual talk, in real time, is called chatting.In chatting, you type a message on your screen, which is immediately received by the recipient; then the recipient can type a message in response to your message, which is received by you instantly.37. What is video conferencing?A two-way videophone conversation among multiple participants is called video conferencing.38. Define web browser and web server.Web browser:A Web browser is a WWW client that navigates through the World Wide Web and displays web pages. Internet Explorer and Netscape Navigator are two most popular web browsers.Web server:A Web server is a WWW server that responds to the requests made by web browsers.

Web sites are hosted on web server.39. What is web hosting?Web Hosting is a means of hosting web-server application (Web sites) on a computer system through which content on the internet is readily available to any web-browser client.40. What is hacking?The activities perform by the hackers are called hacking. Hacker is a slang term for computer enthusiast, i.e., a person who enjoys learning programming languages and computer systems and can often be considered an expert on the subjects. They can use their knowledge for playful pranks.43. What are cookies?Cookies are messages that a Web server transmits to a Web browser so that the Web server can keep track of the user’s activity on a specific web site.44. What is cracking? How is it different from hacking?The activity performed by the cracker is called cracking. The Crackers are the malicious programmers who break into secure systems whereas; Hackers are more interested in gaining knowledge about computer system and possibly using this knowledge for playful pranks.45. What is 80-20 rule of network design?80-20 rule states that:80 percent of the traffic on a given network segment is local, and not more than 20 percent of the network traffic should need to move across a backbone.46. Which of the following (i) is not a broadcast device (ii) offers a dedicated bandwidth?(a) repeater (b) bridge (c) hub (d) switch.(i) is not a broadcast device:Repeater(ii) offers a dedicated bandwidth:switch47. What is web scripting?The process of creating and embedding scripts in a web page is known as web-scripting.A script is a list of commands embedded in a web-page. Scripts may be written for a variety of purposes such as for automating processes on a local-computer or to generate web-pages on the web.48. Name some web scripting languages.Some of the most common ones are: VBScript, JavaScript, ASP, PHP, PERL, JSP, etc.49. What is Cyber Crime?Cyber Crime:Crimes committed with the use of computers or relating to computers, especially through the Internet. Universally, Cyber crime is understood as “an unlawful act where in the computer is either a tool or a target or both”.50. When was IT Act enforced in India?IT Act enforced in India on 17 October 2000.

51.what is XML and DHTML?

Xml is a markup language for documents containing structured information. Structured information contains both content(words, pictures etc..).

DHTML refers to web content that changes each time it is viewed

Short Answer Questions1.What is a network? What are its goals and applications?Network:A network is an “interconnected collection of autonomous computers’.Network Goals:-Resource Sharing.-Reliability.-CostFactor.-Communication Medium.Applications:-Sharing of peripherals, information.-Access to remote database.-Communication Facilities.

2.Briefly explain how Internet evolved.Evolution of networking started way back in 1969 by the development of first network called ARPANET a short of Advanced Research Projects Agencey NETwork. The goal of this project was to connect computers at different universities and U.S. defense. Soon the engineers, scientists, students and researchers who were part of this system, began exchanging data and messages on it. In mid 80’s another federal agency, the National Science Foundation, (NSF) created a new, high capacity network called NSFnet, which was more capable of ARPANET. NSFnet allowed only the academic research on its network and not any kind of private business on it. So many private companies build their own networks, which were later interconnected along with ARPANET and NSFnet to form INTERNET.

4.How does Internet work?In Internet, most computers are not connected directly to the internet. Rather they are connected to smaller networks, which in turn are connected through gateways to the Internet backbone.Internet Functions:-At the source computer, the message/file to be sent to another computer is firstly divided into very small parts called Packets. A packet generally contains some information.-Each packet is given a number serialwise.e.g.,1 , 2, 3.-All the packets are then sent to the address of destination computer.-The destination computer receives the packets in random manner. If a packet is lost it is demanded again.- The packets are reassembled in the order of their number and the original message/file is obtained.

6.How is circuit switching different from message switching?Switching techniques are used for transmitting data across networks.Circuit Switching Message SwitchingIn this technique, first the complete physical connection between two computers is established and then data are transmitted from the source computer to the destination computer. Message Switching works on store and forward principle. In this technique the source computer sends data to the switching office first, which stores the data in its buffer. It then look s for a free link to another switching office and then sends the data to this office. This process is continued until the data are delivered to the destination computers.

7.How does transmission take place across networks?By various switching techniques like circuit switching, message switching and packet switching data are transmitted across network. A transmission media or communication channel carries the data from one point to another.

8.What are communication channels? Discuss various communication channels available for networks.Communication channels are the medium used to carry information or data from one point to another.Various available communication channels are:Guided Media: Twisted Pair Cable, Coaxial Cable, Optical Fibers.UnGuided Media: Microwaves, Radiowaves, Satellites.

10.What is bandwidth? How is it measured?Bandwidth: It refers to the difference between the highest and lowest frequencies of a transmission channel. The term is also sometimes used to refer to the amount of information travelling through a single channel at any one point of time.In digital systems, bandwidth is measured in bps. (bits per second).In analog systems, It is measured in Hz(hertz), kHz(kilohertz), MHz(Megahertz), GHz(gigahertz),THz(Terahertz).

11.What do you understand by data transfer rates?The data transfer rate represents the amount of data transferred per second by a communications channel or a computing or storage device. It is measured in bps(bits per second), bytes per second(Bps) or baud.

12.Discuss and compare various types of networks.A computer network means a group of ‘networked’ computers. There are three types of networks:-Local Area Networks (LANs).-Metropolitan Area Networks (MANs).-Wide Area Networks (WANs).LAN MAN WANSmall computer networks that are confined to a localized area (e.g., an office, a building or a factory) are known as Local Area Network. Rarely LAN computers are more than a mile apart. Metropolitan Area Networks are the networks spread over a city. For example, cable TV networks that are spread over a city. The networks spread across countries are known as WANs. Wide Area Network is a group of computers that are separated by large distances and tied together. For e.g., INTERNET.

15.Compare and contrasti) Star and Bus topologies 2) Star and Tree topologies 3) bus and ring topologies

1) Star and Bus topologies:

Bus topology: All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology. Bus topology was quite popular till about a decade ago, but is now being replaced with the star topology.

Star topology: In the star topology, there will be a central hub/bridge/switch and every computer is connected to it directly. All devices are connected to a centrally. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the central device.

2) Star and Tree topologies

Star topology: In the star topology, there will be a central hub/bridge/switch and every computer is connected to it directly. All devices are connected to a centrally. Star networks are relatively easy to install and manage, but bottlenecks can occur because all data must pass through the central device.

Tree topology: The tree topology is a hybrid where groups of star-configured networks are connected to a linear bus backbone. In this topology the network is shaped like an inverted tree.

(Tree topology)

3) bus and ring topologiesBus topology: All devices are connected to a central cable, called the bus or backbone. Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology.

Ring topologiesIn Ring topology, each node is connected to two and only two neighbouring nodes. Data is accepted from one of the neighbouring nodes and is transmitted onwards to another. In this topology data travels in one direction only, (Clockwise or Anticlockwise) from node to node around the ring. The advantages of using the ring topology are that it needs short cable length and is suitable for optical fibres.

(ring topology)

18.What is the role of a switch in a network?A switch is a device that is used to segment networks into different subnetworks called subnets or LAN segments. It’s a small hardware device. Network switches appears nearly identical to hub, but a switch generally are more intelligent than a hub with a slight higher price tag. Switches are capable of inspecting data packets as they are received, determining the source destination device of each packets & then forward them appropriately by delivering only to the destination device. It offers better performance than hub.

19.Briefly discuss the role of following devices in the context of networking.(i) Repeater (ii) Router(iii) Bridge(iv) Gateway.

i)Repeater:A Repeater is a network device that amplifies and restores signals for long-distance transmission. They are used in long network lines, which exceed the maximum rated distance for a single run. They are of two kinds: amplifier Repeater and Signal Repeater.

ii)RouterA Router is a network device that is used to separate different segments in a network to improve performance and reliability. A router works like a bridge but can handle different protocols. For example a router can link Ethernet to a mainframe.

iii) BridgeA Bridge is a network device that establishes an intelligent connection between two local networks with the same standard but with different types of cables. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Due to this the performance of the network increases.

iv) Gateway.A Gateway is a network device that connects dissimilar network or different types of networks like LAN, MAN, WAN. It establishes an intelligent connection between local network and external networks with completely different structures.

20.What is a communication protocol? What is its role in a network?A protocol means the rules that are applicable for a network. A communication protocol is a formal description of message formats and the set of rules that two or more machines must follow to exchange those messages.

Networks -Higher order thinking skills(HOTS)

Q.1 What is protocol? How many types of protocols are there?

Ans. When computers communicate each other, there needs to be a common set of rules and instructions that each computer follows. A specific set of communication rules is called a protocol.

Some protocol: PPP, HTTP, SLIP, FTP, TCP/IP

Q.2 What is the difference between Networking and Remote Networking?

Ans. The main difference between Networking and Remote Networking, is the network which we use in offices or other places locally such LAN or INTERNET and remote networking is one which we use TERMINAL Services to communicate with the remote users such WAN.

Q.3 What is point-to-point protocol?

Ans. A communication protocol used to connect computer to remote networking services include Internet Service Providers. In networking, the Point-to-Point protocol is commonly used to establish a direct connection between two nodes. Its primary use has been to connect computers using a phone line.

Q.4 How gateway is different from router?

Ans. A gateway operates at the upper levels of the OSI model and translates information between two completely different network architectures. Routers allow different networks to communicate with each other. They forward packets from one network to another based on network layer information. A gateway can interpret and translate the different protocols that are used on two distinct networks. Unlike routers that successfully connect networks with protocols that are similar, a gateway perform an application layer conversion of information from one protocol stack to another.

Q.5 What is the role of network administrator?

Ans. Basic tasks for which a network administrator may be responsible:

a. Setting up and configuring network hardware and software.b. Installing and configuring network media and connections.c. Connecting user nodes and peripherals of all kinds to the network. d. Adding users to and removing users from the network.e. Managing user account.f. Ensuring the security of the network.g. Provide training to the users to utilize the network’s resources.

Q.8 What is the differences between POP3 and IMAP Mail Server?

Ans. IMAP is a standard protocol for accessing e-mail from a local server. A simpler e-mail protocol is Post Office Protocol 3 (POP3), which download mail to the computer and does not maintain the mail on the server.

IMAP, e-mails are stored on the server, while in POP3, the messages are transferred to the client’s computer when they are read.

Q.7 What is the difference between baseband and broadband transmission?

Ans. Baseband is a bi-directional transmission while broadband is a unidirectional transmission.

No Frequency division multiplexing possible in base band but possible in broadband.

SNo Baseband Broadband

1 Entire bandwidth of the cable is consumed by a signal

broadband transmission, signals are sent on multiple frequencies, allowing multiple signals to be sent simultaneously.

2 Digital signals Analog signals

3 bi-directional transmission unidirectional transmission

4 No Frequency division multiplexing possible

Frequency division multiplexing possible

5 Uses for short distance Uses for long distance

Q.8 What are the difference between domain and workgroup?

Ans.

SNo Domain Workgroup

1. One or more computers are servers All Computers are peers.

2. If you have a user account on the domain, you can logon to any computer on the domain.

Each computer has a set of accounts.

3. There can be 100+ computers Typically not more then 20-30 computers

4. The computers can be on different local network

All computers must be on the same local netork.

Q.9 Name different layer of the ISO OSI Model.

Ans. International Standard Organisation – Open Systems Interconnection has seven layers;

Physical Layer

Data Link Layer

Network Layer

Transport Layer

Session Layer

Presentation Layer

Application Layer

Q.10 What is client server architecture?

Ans. To designated a particular node which is well known and fixed address, to provide a service to the network as a whole. The node providing the service is known as the server and the nodes that use that services are called clients of that server. This type of network is called Client-Server Architecture.

Q.11 What is FDM? Give example.

Ans. FDM-Frequency Division Multiplexing is used in analog transmission. It is often used in short distance. It is code transparent and any terminal of the same speed can use the same sub-channel after the sub-channel is established. The best example if FDM is the way we receive various stations in a radio.

Q.13 describe the following in brief:

i) MOSAIC ii) USENET iii) WAIS

Ans. i) MOSAIC: is the program for cruising the internet. The National centre wrote this program for Super Computer application at the university of Illinois. It has a simple window interface, which creates useful hypertext links that automatically perform some of the menu bar and button functions.

ii) USENET: is the way to meet people and share information. Usenet newsgroup is a special group set up by people who want to share common interests ranging from current topic to cultural heritages.

iii) WAIS: is a WIDE AREA INFORMATION SERVER.