Computer Networking

COMPUTER NETWORKING

1.         Define a network.

Ans: A computer network is a system in which computers are connected to share information and resources.

2.         Write two advantages of networks.

Ans: Advantages:

i.          Data or information can be shared among the users.

ii.         Fast communication can be achieved.

iii)        Expensive hardware or software can be shared among the users.

3.         Write two disadvantages of networks.

Disadvantages of networks:

i)          Sophisticated Hardware and software technology is required.

ii)         Expensive to install network.

iii)        Threat to security of data and information.

4.         What is communication channel? Name the basic types of communication channels available.

Ans: Communication channels mean the connecting cables that link various workstations. There are 3 basic types of cables:

i)          Twisted Pair cables     ii)         Coaxial cables             iii)        Fiber-optic cables

5.         What is MAC Address?

Ans: In computer networking, a Media Access Control address (MAC address) is a unique identifier assigned to most network adapters or network interface cards (NICs) by the manufacturer for identification

6.         What is IP address?

Ans: A unique number consisting of 4 parts separated by dots, e.g. 165.113.245.2 every machine that is on the Internet has a unique IP number - if a machine does not have an IP number, it is not really on the Internet.

7.         What is domain name? How is it alternatively known?

Ans: The unique name that identifies an Internet site.

Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general. E.g.: matisse.net

8.         What are the various types of networks?

Ans: Network can be classified on the basis of their size, complexity and geographical spread. On the basis of geographical spread it can be classified as Local Area Network, Metropolitan Area Network and Wide Area Network.

9.         What is the difference between MAN and WAN?

Ans: A metropolitan area network (MAN) is a large computer network that usually spans a city or a large campus. WAN (Wide Area Network) is a network that covers an area larger than a single building or campus such as across the cities or countries.

10.       What is meant by Topology? Name some popular topologies.

Ans: Network topology is defined as the interconnection of the various elements (links, nodes, etc.) of a computer network. In computer networking, topology refers to the layout of connected devices.

•           Bus topology

•           Star topology

•           Ring topology

•           Tree topology

•           Mesh topology

11.       What are the factors that must be considered before making a choice for the topology?

Ans: Cost of Expenses required for implementation of network, Reliability of a particular topology and flexibility of system for future adjustment; are the various factors that must be considered before making a choice for the topology.

12.       What are the similarities and differences between bus and tree topologies?

Ans: In bus topology each machine is connected to a single cable. Each computer or server is connected to the single bus cable through some kind of connector. Tree topology is a network with the shape of an inverted tree in which a single link between two nodes.

13.       What are the limitations of star topology?

Ans: Central node dependency: In this topology central node is a controller of the network. If the central node fails, the entire network will be failed.

Difficult to expand: The addition of a new node to a network involves a connection all the way to the central node.

14.       When do you think, ring topology becomes the best choice for a network?

Ans: In case if we need less connection of wires, very fast communication speed; a ring topology becomes the best choice for a network. This is because optical fiber offers the possibility of very high seed transmissions in one direction.

15.       Write the two advantages and two disadvantages of star topology in network.

Ans: Advantages:

i)          The star topology is considered the easiest topology to design and implement.

ii)         An advantage of the star topology is the simplicity of adding additional nodes.

Disadvantages:

1. Too much dependency on central device has its own drawbacks. If it fails whole network goes down.
2. The use of hub, a router or a switch as central device increases the overall cost of the network.
3. Performance and as well number of nodes which can be added in such topology is depended on capacity of central device.

16.       Write the disadvantages if twisted pair cables.

Ans:

i)          A twisted pair cable is incapable carrying a signal over long distances without the use of repeaters.

ii)         Its low bandwidth capabilities are unsuitable for broadband applications.

iii)        Its supports maximum data rates 1mbps without conditioning and 10 mbps with conditioning.

17.       Define Hub.  

Ans: The central connecting device in a computer network is known as a hub. When data packets arrives at hub, it broadcast them to all the LAN cards in a network and the destined recipient picks them and all other computers discard the data packets.

18.       Define switch.

Ans: A Switch is a device that is used to segment networks into different sub networks called subnets or LAN segments. Segmenting the network into smaller subnets, prevents traffic overloading in a network.

19.       What are the goals of network?

Ans: Resource sharing: The aim to make all programs, data and peripherals available to anyone on the network irrespective of the physical location of the resources and the users.

Reliability: A file can have copies on two or more machines, so if one of them is unavailable due to hardware or software crash, the other copies could be used. E.g.: Railway reservation, Airways reservation etc.

Cost Factor: Personal computers have better price / performance ratio as the important data are stored on file server machine available for sharing.

Communication Medium: Using a network, it is possible for managers, working far apart, to prepare financial report of the company. The changes at one end can be immediately noticed at another and hence it speeds up co-operation among them.

20.       Write the applications of network?

Ans: Application of networks:

        i.            Sharing of Computer peripherals among the connected users.

      ii.            Sharing Data or information among the connected users.

    iii.            Access to remote database: User can access to remote database sitting at his home to make reservation for airplanes, trains hotels and so on anywhere in the world with instant confirmation.

    iv.            Communication facilities: Using Network, user can share text, images, digitized voice or movie to any users anywhere in the world.

      v.            Cost deduction: Using Computer Network communication system, amount required for travelling of user or data from one location to another can be reduced to very less and also saves energy for the same.

21.       What do you understand by domain name resolution?

Domain Name Resolution is the task of converting domain names to their corresponding IP address. This is all done behind the scenes and is rarely noticed by the user. When you enter a domain name in an application that uses the Internet, the application will issue a command to have the operating system convert the domain name into its IP address, and then connect to that IP address to perform whatever operation it is trying to do.

22.       What are communication channels? Discuss various channels available for networks?

Ans: Communication channels mean the connecting cables that link various workstations. There are 3 basic types of cables:

a.         Twisted Pair cables                 b.         Coaxial cables             c.         Fiber-optic cables

Coaxial Cables: A cable consisting of two concentric conductors (an inner conductor and an outer conductor) insulated from each other by a dielectric; commonly used for the transmission of high-speed electronic data and/or video signals.

Fiber Optic Cables: It is flexible optically transparent fiber, usually made of glass or plastic, through which light can be transmitted by successive internal reflections.

Twisted Pair: A cable composed of two small insulated conductors twisted together without a common covering. Also known as copper pair. Twisted pairs have less bandwidth than coaxial cable or optical fiber.

23.       Advantages and disadvantages of the followings:

i)          optic fiber

ii)         coaxial cables

iii)        twisted pair cables

iv)        radio waves

v)         microwaves

Ans:

(i): Optic fiber:

Advantage:                 i. It is free from electrical noise and interference

ii. It has more bandwidth than copper wire.

Disadvantage:                         It is an expensive communication medium.

(ii) Coaxial cables:

Advantage :                i. It provides a cheap means of transporting multi-channel television signals around

                                    metropolitan areas.

Disadvantage:                         Expensive than twisted pair cables.

(iii) Twisted pair cables:

Advantage:                 It is inexpensive.

It is easy to install and maintain.

Disadvantage:                         It has low bandwidth capabilities.

It is unsuitable for broadband connection.

(iv) Radio Wave:       A data transmission by use of radio frequencies is called as radio-wave transmission.

Advantages:                i. Radio waves transmission offers mobility.

                                    ii. It proves as cheaper communication system.         

                                    iii. It offers ease communication over difficult terrain.

Disadvantages:            i. It is an insecure communication system.

ii. Radio Signals are susceptible to weather condition like thunder storms, rains etc.

v) Microwave: A microwave communication system is a communications system that uses a beam of radio waves in the microwave frequency range to transmit video, audio, or data between two locations, which can be from just a few feet or meters to several miles or kilometers apart. Microwave links are commonly used by television broadcasters to transmit programmes across a country, or from an outside broadcast back to a studio.

Advantage:                 i. It is cheaper communication system

ii. . It offers ease communication over difficult terrain.

iii. It offers ease communication over oceans.

Disadvantage:            i. It is an insecure communication system.

ii. Radio Signals are susceptible to weather condition like thunder storms, rains etc.

iii. Signals from single antenna may split up and propagate in slightly different path and hence reduces the signal strength.

24.       Explain mostly used topologies.

Star topology is widely used due to following reasons:

i)          The star topology is considered the easiest topology to design and implement.

ii)         An advantage of the star topology is the simplicity of adding additional nodes.

25.       What are hubs? What are its types?

A hub is hardware device used to connect several computers together. It is of two types Active or passive Hubs. Active hub is one which amplifies the signal as it moves from one connected device to another. Passive hub allows the signal to pass from one computer to another computer without any change.

26.       What is the role of a switch in a network?

A Switch is a device that is used to segment networks into different sub networks called subnets or LAN segments. Segmenting the network into smaller subnets prevents traffic overloading in a network. A switch is responsible for filtering i.e. transforming data in a specific way and for forwarding packets (a piece of message) between LAN segments. Switch support any packet protocol. LANs that are segmented through switches are called switched LANs.

27.       Discuss repeater.

Ans: Repeater is a device used in data communication to strengthen a signal as it is passed along the network cable. There are two types of Repeater:

Amplifier: It amplifies all incoming signals as well as concurrent noise.

Repeater: It regenerates the packet as if it is starting from the source station.

28.       What are common threats to network security?

Ans: The various threats to network security are as follows:

Intrusion Problems / Access Attacks: This occurs when an unauthorized user attempts to protected sensitive / confidential information. It may be of following types:

Snooping: It refers to unauthorized access to someone else’s data, email or computer activity.

Eavesdropping: It refers to unauthorized listening / intercepting someone else’s private communication / data/ information.

Denial-of-services attacks: DoS are those attacks that prevent the legal users of System from accessing or using the resources, information or capabilities of the system. It may be of following types:

a.         Denial of Access to Information: Such attacks causes deletion or changing of important information to non readable format.

b.         Denial of Access to Applications: Such attacks makes the applications unusable or unavailable for legal user of the system.

c.         Denial of Access to Communications: Such attacks includes cutting of communication wire, jamming radio communications, flooding a system with junk mail.

29.       What are denial of services attacks?

Ans: Denial-of-services attacks: DoS are those attacks that prevent the legal users of System from accessing or using the resources, information or capabilities of the system. It may be of following types:

Denial of Access to Information: Such attacks cause deletion or changing of important information to non readable format.

Denial of Access to Applications: Such attacks make the applications unusable or unavailable for legal user of the system.

Denial of Access to Communications: Such attacks includes cutting of communication wire, jamming radio communications, flooding a system with junk mail.

30.       How can you prevent/ counter threats of network security?       

Ans: Threats of network security can be prevented by using various techniques:

i)          Authorization: In this case User is asked to enter an authorized login-id. If user is able to provide legal login-id then he/she is considered as authorized user.

ii)         Authentication: In this case User is asked to enter a legal password. If user is able to provide legal password then he/she is considered as authenticate user.

iii)        Firewall: Firewall is a mechanism to prevent unauthorized internet user to access private network connected to internet.

iv)        Intrusion Detection: This is a monitoring system which detects unauthorized access of data or resources of the network.

Assignment No. 1

SHORT ANSWER QUESTION

1. Define a network? Why is it needed?

2. What is an IP Address? How is it different from MAC address?

3. What is a domain name? How it is alternatively known?

4. What is the difference between MAN & WAN?

5. What is meant by topology? What are the factors that must be considered before making a choice for the topology?

6. Give two advantages & two disadvantages of :-(a) Star (b) Bus

7. Define the following :-(a) Hub (b) Firewall(c) Switch (d) Bluetooth

8. What is snooping?

9. What is eavesdropping?

10. Define Internet? Name some services offered by the Internet.

11. What do you understand by Domain Name Resolution?

12. What are communication channels? Discuss various communication channels available for network?

13. Write some advantages and disadvantages of the following?

(a) Optical Fiber (b) Co-axial cable (c) Twisted Pair wires (d) Radio Waves (e) Microwave (f) Satellites

14. Discuss & compare various types of networks?

15. Compare and contrast:-

(a) Star & Bus topologies (b) Star & Tree topologies (c) Bus & Ring topologies

16. What are hubs? How it is different from switch?

17. Briefly discuss the function of: - (a) Repeater (b) Gateway (c) Switch

18. What do you mean by system Security? What are common threats to network security?

19. What is Denial of Services (DoS) Attacks?

20. How can you prevent yourself from various threats of network security?

CBSE IMPORTANT  QUESTIONS

1          Two doctors in the same room have connected their palm tops using Bluetooth   for working on a group presentation. Out of the following, what kind of networks they have formed? LAN,MAN,PAN,WAN.           

Ans: PAN                   

2          Which transmission medium should be used to transfer data across two continents at very high speed?           

Ans: SATTELITE

3          Explain the difference between domain name and URL with the help of appropriate example of each.

Ans: Domain is a unique name assigned to a website.

4          Differentiate star and bus topology of networks. Write the two advantage and two disadvantages of the following topologies in network

Bus Topologies  (ii) Star Topologies

Ans: Star Topology:

                 Advantage:  1. Ease of service.

                                       2. Centralized control/ problem diagnosis.

                  Disadvantage:   1. Long cable length.

                                              2. Difficult to expand

         Bus Topology:

                 Advantage:  1. Short cable length & simple wiring layout.

                                       2. Easy to extend

                  Disadvantage:   1. Fault diagnosis is difficult.

                                              2. Nodes must be intelligent.   

5          Explain in brief of networking needs and goals.   

Ans: Network Needs:

i.          Resource Sharing:  The aim is to make all programs,data and peripheral available to anyone on the network   irrespective of the physical location of the resources and the user.

ii.         Reliability: A file can have copies on two or three different machines, so if one of them is unavaible ( hardware crash), the other copies could be used.

iii.        Cost Factor:  Personal computers have better price/performance ratio than micro computers. So it is better to have PC’s , one per user, with data stored on one shared file server machine.

iv.        Communication Medium: Using a network, it is possible for managers, working far apart, to prepare financial report of the company. The changes at one end can be immediately noticed at another and hence it speeds up co – operation among them.          

6          Which protocol is used for transfer files over the internet?

Ans: FTP

7          Differentiate between a hub and a switch.

Ans: Hub:  A hub is a hardware device used to connect several computers together. A hub that contains multiple independent but connected modules of network and inter – networked equipment.

There are two types of hub:

1.         Active Hub

2.         Passive Hub

Switch: A switch is a device that is used to segment networks into different sub networks called subnets or LAN segments. Segmenting the network into smaller subnets, prevent traffic overloading in a network. A switch is responsible for filtering i.e. transforming data in a specific way and for forwarding packets between LAN segments.

8          Write the purpose of the following:  i. Infrared ii. Microwave

Ans: Microwave:  Microwave signals are used to transmit data without the use of cables. The microwave signals are similar to radio   and television signals and are used for long distance communication.

Infrared: This type of transmission uses infrared light to send data. The infrared light transmits data through the air and can propagate throughout a room, but all not penetrate walls.                                       

9          What type of network would you suggest for following type of requirements of an organization. Around 200 computers in two different buildings adjacent to one another are to be connected.

Ans: LAN ( Local Area Network)

10        When would you prefer switch over a hub?

Switch: A switch is a device that is used to segment networks into different sub networks called subnets or LAN segments. Segmenting the network into smaller subnets, prevent traffic overloading in a network. A switch is responsible for filtering i.e. transforming data in a specific way and for forwarding packets between LAN segments.

Hub:  A hub is a hardware device used to connect several computers together. A hub that contains multiple independent but connected modules of network and inter – networked equipment.

11        Name two guided transmission media for networking.

Ans: 1. Coaxial         2. Fiber Optic

12        Which protocol is used for transfer of hyper text documents on the internet?

    Ans: HTTP

13        A School would like to go in for network of all the computers. Which topology would you recommend and why?

Ans: Bus Topology

14        What is communication channel? What choices do you have while choosing a communication channel for a network?

Ans: The communication channel is the connecting cables or connecting media. The cables that connect two or more workstations are the communication channels.

15        What do you mean by network topology? Name most popular topologies

Ans: The pattern of interconnection of nodes in a network is called the Topology. Popular topologies are: Star topology, bus or linear topology, ring topology, tree topology, mesh topology.

16        Navneet is using software, which has been downloaded from internet and is available for one month. After one month he has to pay license fee for further use. What software Navneet is using?

Ans: Shareware

17        Akhil is transferring songs from his mobile to his friend’s mobile via Bluetooth connection. Name the network used by Akhil.

Ans: PAN (Personal Area Network)

18        Name a network to connect computers and other devices in a relatively small space.

Ans: PAN

19        A bank is planning to link its branches situated in various parts of the same city which type of network will be formed?

        Ans: LAN

20        What is mean by sites Identification on Internet?

Ans: In general, a domain name represents an Internet Protocol (IP) resource, such as a personal computer used to access the Internet, a server computer hosting a web site.

21        Most common communication protocol on Internet.

Ans: TCP/IP

22        Mr Ram is interested in transferring songs from his mobile to Mr Shyam’s mobile. Suggest two suitable wireless options he may use for doing the same.

Ans: Bluetooth, Zigbee

23        Name the protocol used for sending and receiving e-mails.         

Ans: SMTP

24        What is the difference between Star Topology and Bus Topology of network?            

Ans: Star Topology: This topology consists of a central node to which all other nodes are connected by a single path.

Bus Topology: This consists of a single length of the transmission medium onto the various nodes are attached.

25        Differentiate between MAC address and IP address.

Ans: MAC Address  refers to the physical address assigned by NIC manufacturer. A MAC address is a 6 byte address with each byte separated by a colon.

IP Address:  Every machine on a TCP/IP network has a unique identifying number called an IP address. IP address are 32 bit address.      

26        Define:   IP Address, Bridge, Repeater

IP Address:  Every machine on a TCP/IP network has a unique identifying number called an IP address. IP address are 32 bit address.                                                                              

Bridge: A bridge is a device which is used to connect two local area networks or two segments of the same LAN

Repeater: A repeater is a network device that amplifies and restores signals for long-distance transmission

27        Write the purpose of (i) Repeater (ii) Router

Repeater: A repeater is a network device that amplifies and restores signals for long-distance transmission

Router: A router is a network device that connects multiple networks irrespective of their protocol.

28        Which network topology requires terminators at the ends of the lines?

Ans: BUS

29        Write two snooping methods used by hackers/crackers.

Ans: i) Snooping         ii) Eavesdropping

30        Mr. Ajeet is interested in transferring songs from his mobile to Mr Rahul mobile. Suggest two suitable wireless options he may opt for doing the same    

Ans: BLUETOOTH, ZIGBEE

31        What is snooping and phishing?          

Snooping: refers to unauthorized access of someone else’s data, email, computer-activity, or data communication          

Phishing:  Phishing is the attempt to acquire sensitive information such as usernames, passwords, and credit card details and sometimes, indirectly, money in an electronic communication.

32 Two doctors in the same room have connected their Palm Tops using Bluetooth for working on a Group presentation. Out of the following, what kind of Network they have formed?  (LAN, MAN, PAN, WAN)

 Ans: PAN

33 Why network security is an important aspect over data security                   

Ans: A computer infection can propagate throughout its connections with minutes to hour’s time. This is the reason that network security has become an important.

34 What type of address is the following? Also define it.

20: B9: F1: 63: 2F: FB

Ans: MAC (Media Access Control)

35        Identify the topologies from the following.

In it the nodes form a circular path for data to travel and each node is connected to two other nodes. It consists of a central node to which all other nodes are connected by a single path.

Ans: Ring topology

36        Define: i) WORM ii) Trojan Horse

Ans: Both are Virus, WORM stands for Write Once Read Many, it occupies the total disk space

Trojan Horse is a Virus that effect the FAT (File Allocation Table) and eats up entire disk space

37        Write short note on Firewall.

Ans: A system designed to prevent unauthorized access to or from a private network is called Firewall