Model Question Paper

Subject Code: MC0075

Subject Name: Computer Networks

Credits: 4 Marks: 140

Part A (One mark questions)

1. A node, which is more powerful, and can handle local information processing or graphics

processing is called a------------------.

a. Workstation

b. Server

c. Network Operating System

d. Peer system

2. …………………… have a single communication channel that is shared by all the users on the

network.

A) Point-to-point

B) Broadcast networks

C) Protocol

D) PAN

3. Which Layer is Responsible for Congestion Control?

A) Network Layer

B) Datalink Layer

C) Transport Layer

D) Application layer

4. ………………….is a technique of conversion between the representation of digital data in

user equipment and the corresponding signals transmitted over a communications channel.

A) Line coding

B) Demodulation

C) Modulation

D) Segmentation

5. Videoconferencing is an example for…………………… communication

a. Simplex

b. Half duplex

c. Full duplex

d. serial

6. E-mail is an example of ………………………… mode of communication where one party can

send a note to another person and the recipient need not be online to receive the e-mail.

a. asynchronous

b. synchronous

c. full duplex

d. either A or B

7. …………………………..combines characteristics of linear bus and star topologies.

A) Ring topology

B) A hybrid topology

C ) A tree topology

D) mesh topology

8. Following are the advantages of tree topology

i) Point-to-point wiring for individual segments.

ii) Supported by several hardware and software venders.

iii) Easy to install and wire

a. i) only

b. i) and ii) only

c. iii) only

d. i) ,ii) and iii)

9. Which of these is an example for unguided transmission?

A) coaxial cable

B) optical fibers

C) wireless

D) twisted pairs

10. The key concern in the design of transmission system is -------------- and --------------- a. data rate ,distance

b. speed, accuracy

c. accuracy, simplicity

d. distance , cost

11. Which of the following transmission media suffers more from transmission impairment?

a. coaxial cable

B) Optical fiber

c. twisted pair

D) wave guides

12. The Hamming Distance for the codes generated using either even or odd parity will be--------

----------

a. 2

b. 4

c.1

d. 0

13. Pure ALOHA has a maximum throughput of ----------- a. 16.4 %

b. 18.4 %

c. 7.4 %

d. 1 %

14. preamble field of 802.3 frames is encoded using ------------------- encoding A) Manchester

B) differential Manchester

C) Bi polar

D) uni polar

15. ----------------is a static algorithm in which every incoming packet is sent out on every outgoing line except the one it arrives on.

A) Distance vector

B) Congestion

C) Link state routing

D ) Flooding

16. Where are routing tables placed?

A) in network interface card

B) in routers memory

C) in server memory

D) in a subnet’s memory

17. Which of these is a minimal message-oriented transport layer protocol?

A) UDP

B) SMTP

C) HTTP

D)TCP/IP

18. --------------- is/are used for error detection.

A) Parity bit

B) checksum

C) both A) and B)

D) neither A) nor B).

19. Which of these is a feature of hubs? A) Hubs amplify the incoming signal.

B) Hubs understand frames, packets or headers

C) All lines coming into a Hub must operate at a same speed.

D) all of these

20. DSL stands for ------------------------ A) data subscriber lines

B) dual subscriber lines

c) delay subscriber lines

d) digital subscriber lines

21. The packet transmit using standard Internet Protocol(IP) throughout the Internet by

a. Circuit switching

b. Packet switching

c. Message switching

d. None of the above.

22. Which of the following is required to communicate between two computers?

a. Communications software

b. Protocol

c .Communication hardware

d. All of the above including access to transmission

medium

23. The special address 'THIS HOST' is referred to as

a. 0.0.0.0

b. 0.0.14.98

c. 127.0.0.127

d. 255.255.255.255

24. How many number of host/machine can be attached to a network using a class B address?

a. 65,536

b. 128

c. 256

d. 16,777,216

25. This mapping of name to IP address is done by …………………………….

a. Address resolution protocol

b. Domain name server

c. reverse address resolution protocol

d. Ethernet

26 Destination physical address in ARP request is a ………………………….address.

a. Unicast

b. Broadcast

c . Multicast

d. Anycast

27. ARP is defined in RFC _____ and it is a current internet standard, ________

a. RFC-37, STD 903

b. RFC-903, STD 37

c. RFC 826; STD 37

d. RFC 37; STD 826

28. The idea of sharing one network address among the multiple physical networks can be done

using the following technique:

a. Supernetting

b. Subnetting

c. Transparent router

d. Both b & c

29 . What are the subnet mask in dotted decimal notation for /20 networks?

a. 255.255.252.0

b. 255.255.255.0

c. 255.255.254.0

d. 255.255.240.0

30. ICMP messages require

………………. levels of encapsulation

a. One

b. Two

c. Three

d. Four

31. A router receives an IP packet with source IP address 130.45.3.3 and destination IP

address 202.23.4.16. The router cannot find the destination IP address in its routing table.

Which ICMP message should be sent?

a.Time stamp request

b. Router solicitation

c.Destination Unreachable

d. Parameter problem on a datagram

32 In an autonomous system with n areas, how many areas are connected to the backbone?

a. 1

b. N

c. N+1

d. N-1

33. OSPF is based on …………………

a. Distance vector routing

b. Path vector routing

c. Link state routing

d. both a and b

34. Which type of BGP message is sent by a system to notify another router of the sender’s existence? a. Keep-alive

b. Notification

c. Open

d. Update

35. What is the length of MARKER field in BGP message header?

a. 1 byte

b. 2 byte

c. 16 byte

d. 19 byte

36. Internet e-mail system based on the ……………………………………………..

a. FTP

b. Simple Mail Transfer Protocol (SMTP)

c. POP

d. Both SMTP and POP

37. Which function is not supported by E-mail? a. authentication

b. composition

c. Disposition

d. Displaying 38. FTP servers by default listen on port ________ for incoming connections from FTP clients.

a. 20

b. 21

c. 23

d. 25

39. In the symmetric-key method of cryptography, which key is publicly known?

a. Encryption key only b. Decryption key only c. Both d. None of the above

40. If user A wants to send an encrypted message to user B, the plaintext is encrypted with the

public key of ………….

a. Skeleton

b. Private

c. Public

d. Symmetric

Part B (Two mark questions)

41. The worldwide Internet is a well-known example of ------------------.

A) PAN

B) Subnet

C) Intra-Network

D) Inter-network

42. ------------------- is/ are caused by the random motion of the electrons in a wire and is unavoidable. a. Dispersion

b. Thermal noise

c. Delay distortion

d. all of these

43. Match the following

1) FDM i)Light streaming 2) TDM ii) internet 3) WDM iii) analog communication 4) Packet switching Iv) digital communication

A) 1-iv, 2- i, 3-ii, 4- iii

B) 1-ii, 2-i,3-iv, 4-iii

C) 1- iii, 2-iv , 3-i, 4-ii

D) 1-iii, 2-i, 3-ii, 4-iv

44. Transmission medias are classified into two main categories, which are -------------- and --------------------. A) twisted pair, coaxial

B) guided , unguided

C) analog, digital

D) synchronous, Asynchronous

45. Match the following

1. CAT3 cable i) high speed computer communication 2. CAT5 cable ii)2 GHz t0 40 GHz 3. CAT6 & CAT 7 cable iii) 16 to 100 MHz 4. wireless transmission iv) 250 MHz to 600 MHz

A) 1-iii, 2-I 3-iv, 4-ii

B) 1-iii, 2-iv 3-ii 4-i

C) 1-ii, 2-iii, 3-iv 4-i

D) 1-iv 2-iii, 3-i 4-ii

46. What is the pattern of a preamble?

A) 11110000

B) 11111111

C) 00000000

D) none of these

47. State true or false i) Low bandwidth lines cause congestion ii) Slow processors cause congestion. iii) Adding more memory increase congestion

A) true, true, false

B) false ,true, false

C) true, false , false

D) true , true, true

48. In ----------------------- configuration, the switch begins to forward the packet as soon as it is

received. No error checking is performed on the packet, so the packet is moved through very

quickly.

a. cut-free

B) franment-free

C ) store-and-forward

D) cut-through

49. Which of these cable is/are used to connect devices to hubs and switches.

A) crossover

B) straight-through

C) co-axial

D) both A) and B)

50. A modem is a card within a PC that converts the …………... the computer produces to

………………….. that can pass over telephone system.

a. Data, signal

b. Analog signal, digital signal

c. Digital signal, analog signal

d. signal, data

51. The network interface layer specifies how to organize data into………………………..and Internet layer specifies the format of …………………….. Sent across an Internet. a. Bits, message.

b. frame,packet.

c. packet, messge.

d. datagram, packet.

52. Using a class B address maximum of …………………networks can be defined with up

to……………………..hosts per networks.

a. 2,097,152-------------254

b. 16,384-----------------65,536

c. 16,384---------------65,534

d. 126--------------------16,777,214

53 ARP is defined in RFC _____ and it is a current internet standard, ________

a. RFC-37, STD 903

b. RFC-903, STD 37

c. RFC 826; STD 37

d. RFC 37; STD 826

54. If the organization allocates 10 bits as subnet number, to identify a physical network, then

the organization can have at the most……………. networks and each of these networks that

can support only…………………...hosts.

a. 1022 networks, 62 hosts.

b. 62 networks, 1022 hosts.

c. 4094 networks, 14 hosts.

d. 14 networks, 4094 hosts.

55. A time exceeded message is generated if ………………………………………………….

a. The round trip time between hosts is close to zero.

b. The Time-to Live field has a zero value.

c. Fragments of a message do not arrive within a set time

d. both b & c

56. In distance vector routing an active router sends out information ………………………….

a. Only when there is a change in its table

b. Only when a new host is added

c. At regularly scheduled intervals

d. Only when a new network is added

57. Router B receives an update from router A that indicates Net1 is two hops away. The next

update from A says Net1 is five hops away. What value is entered in B's routing table for Net1?

Assume the basic RIP is being used.

a. 6

b. 7

c. 2

d. 3

58 BGP is …………………………………….routing protocol used to

………………………….routing table.

a. intrautonomous system, update b. Interautonomous system, update

c. Interautonomous system, create

d. intrautonomous system, create

59. In an active mode if any FTP client sends the port command "PORT 192,168,0,1,4,1" then

what will be the interpretation of port field?

a. 1024 b. 1025

c. 1023

d. 227 60. In an authentication using symmetric keys, if 10 people need to communicate, we need

_______ keys.

a. 90

b. 10

c. 20

d. 45

Part C (Four mark questions)

61. Match the following.

1. Physical Layer i) Dialogues control 2. Network Layer ii) Raw bits 3. Session Layer iii) Data encryption 4. Presentation Layer iv) Routing Packet A) 1-iii, 2-iv, 3- ii ,4-i B) 1-ii, 2-iv, 3-i , 4-iii C) 1-iii, 2-ii,3-iv,4-i D) 1-iv,2-iii,3-i,4-ii

62. What are the advantages of synchronous communication?

1. it reduces overhead bits

2. The character is self-contained & Transmitter and receiver need not be synchronized

3. It overcomes the two main deficiencies of the asynchronous method, that of inefficiency

and lack of error detection.

4. Transmitting and receiving clocks are independent of each other

A) 1,2, and 3

B) 1 and 3

C) 1,2 and 4

D) 1,2,3 and 4

63. State true or false

i) The Hamming Distance for the codes generated using either even or odd parity will be 2.

ii) The DLL translates the physical layers raw bit stream into discrete units called packets

iii) The network layer wants messages to be delivered to the remote peer in the exact same order as they are sent.

iv) The data link layer is split into MAC and LLC sub layers.

A) true, true, true true

B) true, false , true, false

C) true, false, true, true

D) true, true, false, false

64 What is the pattern of a preamble? A) 11110000

B) 11111111

C) 00000000

D) none of these

65. State true or false

i. The connection establishment protocol introduced by Tomlinson is known as a three way

handshake.

ii. Asymmetric release is the way the telephone system works.

iii. The 16-bit checksum field is used for error-checking of the header and data.

A) false, false, false

B) true, true, true

C) true, false, false

D) false, false, true

66. Match the followings: Part A 1). Internet layer services 2). Transport layer services 3). Application layer services Part B A. WWW, E-mail, remote login, FTP B. Connectionless packet delivery service and reliable stream transport service C. TCP a. 1. C, 2. A, 3. B

b. 1. A, 2. C, 3. B

c. 1.C, 2. B, 3. A

d. 1.B, 2.A, 3. C

67. State weather the following statements are true or false. 1). FDDI can be used as backbone 2). Frame relay cannot used to connect computers in one city with computers in another 3). The purpose of internetworking is to establish communication between any two computers, that are attached to any two different networks. a. 1. True, 2. true, 3. true

b. 1. True, 2. False, 3. true

c. 1. True, 2. False, 3. False

d. 1. False, 2. true, 3.False

68. Match the dotted decimal notation of IP address with binary notation of IP address: Part A) 1) 129.11.11.239, 2) 221.34.7.82 3) 193.131.27.255 Part B) a. 11011101 00100010 00000111 01010010 b. 11000001 10000011 00011011 11111111 c. 10000001 00001011 00001011 11101111 a. 1. C, 2. A, 3. B

b. 1.C, 2. B, 3. A

c. 1. A, 2. C, 3. B

d. 1.B, 2.A, 3. C

69. match the followings:

Part A

1) ARP request

2) RARP reply

3) Broadcasting the ARP request packet is too expensive

Part B

A. Message: This is your IP address

B. ARP cache

C. the destinations physical address is equivalently FF-FF-FF-FF-FF-FF.

a. 1.C, 2. A, 3. B

b. 1.C, 2. B, 3. A

c. 1. A, 2. C, 3. B

d. 1.B, 2.A, 3. C

70. State weather the following statement is true or false.

1. Route flapping within the private network does not affect the Internet routing table.

2. A class C address can accommodate more than 254 hosts.

3. CIDR reserved for private networks are known as routable addresses

a. 1. True, 2. False, 3. False

b. 1.True, 2. False, 3. True

c. 1.False, 2.False, 3. False

d. 1.True, 2.True, 3. False

71. Fill in the blanks. 1. In error reporting the encapsulated ICMP packet goes to _______. 2. A ______ can learn about network ______ by sending out a router-solicitation packet. 3. To determine whether a node is reachable, _______ message can be sent.

a. The receiver, Router, routers, Redirection

b. A router, Router, hosts, echo-reply

c. The sender, Host, routers, echo-request

d. The sender, Host, hosts, Destination-unreachable

72. match the followings:

Part A

a) Database description messages

b) HELLO message

c) Link state update messages

Part B

1)A router sends this message to broadcast information about its directly connected links to all

other routers

2) Routers exchanges this messages to initialize their network topology database.

3)When a router boots, it sends this message on all point to point links and multicast them on

LANs to the group consisting of all other routers on WANs.

a. a.2, b.3, c.1

b. a.1, b 2, c.3

c. a.2, b.1, c.3

d. a.1, b.3, c.2

73. State weather the following statement is true or false for

1) BGP does not support CIDR

2) BGP does not support load sharing on routers between arbitrary ASes

3) BGP conserves network bandwidth

a. 1. True, 2. true, 3. True

b. 1. true, 2. false, 3. False

c. 1. false, 2. false, 3. False

d. 1.false, 2. true, 3. true

74. Match the followings:

Part A

1) Very Easy Rodent-Oriented Net-wide Index of Computerized Archives.

2) WWW

3) IRC

4) URL

Part B

A) It is open-ended in the sense that it is straight forward to have browsers use multiple

protocols to get at different kinds of resources.

B) It is an architectural frame work for accessing linked documents spread out over millions of

machines all over the internet.

C) It is a search engine system for the Gopher protocol.

D) It is a multi-user, multi-channel chatting system, based on a client-server model.

a. 1.C, 2.B, 3.D, 4.A

b. 1.A, 2.C, 3.D, 4.B

c. 1.B, 2.A, 3.C, 4.D

d. 1.A, 2.B, 3.C, 4.D

75. State weather the following statement is true or false for

1) If a message is digitally signed, any change in the message will invalidate the signature.

2) A one-way hash function takes some ciphertext and translates it into a specific hash.

3) Kirchhoff’s principle states “all algorithms must be private and only the keys open”.

a. 1.True, 2. False, 3.true

b. 1.true, 2.true, 3. False

c. 1.True, 2.False, 3.False d. 1.false, 2. true, 3. False

Answer Keys

Part - A Part - B Part - C

Q. No. Ans. Key Q. No. Ans. Key Q. No. Ans. Key Q. No. Ans. Key

1 A 21 B 41 D 61 B

2 B 22 D 42 B 62 B

3 C 23 A 43 C 63 C

4 C 24 A 44 B 64 D

5 C 25 B 45 A 65 B

6 A 26 B 46 D 66 C

7 C 27 C 47 D 67 B

8 B 28 D 48 D 68 A

9 C 29 D 49 D 69 A

10 A 30 B 50 C 70 A

11 C 31 C 51 B 71 C

12 A 32 D 52 C 72 A

13 B 33 C 53 C 73 D

14 A 34 A 54 A 74 A

15 D 35 C 55 D 75 C

16 B 36 B 56 C

17 A 37 A 57 A

18 C 38 B 58 B

19 C 39 D 59 B

20 D 40 D 60 D