Computer Science - Computer Networks – Multiple Choice Question

Question 1 of 61

1. Question

Protocols are

agreements on how communication components and DTE's are to communicate
logical communication channels used for transferring data
physical communication channels used for transferring data
none of the above

Question 2 of 61

2. Question

The method of communication in which transmission takes place in both directions, but only in one direction at a time is called

simplex
four wire circuit
full deplex
half duplex

Question 3 of 61

3. Question

Error detection at the data link level is achieved by

bit stuffing
cyclic redundancy codes
Hamming codes
equalization

Question 4 of 61

4. Question

Which of the following is a wrong example of a network layer?

Internet Protocol (IP)-ARPANET
X.25 Packet Level Protocal (PLP)-ISO
Source routing and domain naming-USENET
X.25 level 2-ISO

Question 5 of 61

5. Question

The topology with highest reliability is

bus topology
star topology
ring topology
mesh topology

Question 6 of 61

6. Question

baud means

the number of bits transmitted per unit time
the number of bytes transmitted per unit time
The rate at which the signal changes
none of the above

Question 7 of 61

7. Question

Start and stop bits are used in serial communication for

error detection
error correction
synchronization
slowing down the communication

Question 8 of 61

8. Question

Unmodulated signal coming from a transmitter is known as

carrier signal
baseband signal
primary signal
none of the above

Question 9 of 61

9. Question

Manchester code is a

Bi-polar code
non return to zero code
polar code
none of the above

Question 10 of 61

10. Question

Pick the incorrect statements.

Another name for primary/secondary protocol is master/slave.
Peer to peer protocol provides equal status to all sites on the channel.
priority, non-priority types come under master/slave protocol.
TDM is a primary/secondary non-priority system

Question 11 of 61

11. Question

Pick the correct statements.

A switched circuit is a dial-up circuit that may encounter blockage (busy signal)
Non switched leased line supports higher data volume and quality than switched lines
Non switched lines are expensive for high volume data.
Switched circuit provides faster response time.

Question 12 of 61

12. Question

Pick the incorrect statements that pertain to error retransmission used in continuous ARQ method.

Go-back-N method requires more storage at the receiving site.
Selective Repeat involves complex login than Go-back-N
Go-back-N has better line utilisation.
Selective Repeat has better line utilisation.

Question 13 of 61

13. Question

In the carrier sense network if the prevailing condition is a ‘channel busy’, then which of the following are correct?

If the technique used is non-persistent then it results in randomised wait and sence.
If the technique used is 1-persistent then the channel is continually senced.
If the technique used is p-persistent then randomised retransmission is done
If the method used is non-persistent then continuous sensing results.

Question 14 of 61

14. Question

Which of the following are non-poling systems?

TDMA
Stop and Wait
xon/xoff
Continuous ARQ

Question 15 of 61

15. Question

Pick the sytems that can be used in both priority and non-priority modes.

TDM
Register insertion
Carrier sense systems
Token passing

Question 16 of 61

16. Question

How many characters per sec (7 bits + 1 parity) can be transmitted over a 2400 bps line if the transfer is synchronous (1 start and 1 stop bit)?

300
240
250
275

Question 17 of 61

17. Question

How many characters per sec (7 bits + 1 parity) can be transmitted over a 2400 bps line if the transfer is asynchronous (1 start and 1 stop bit) ?

300
240
250
275

Question 18 of 61

18. Question

Match the following
1) session layer (i) connects DCE into physical channel
2) Transport layer (ii) provides end to end accountability
3) Application layer (iii) provides organised means to exchange data between users.(like synchronisation points)
4) MDI (Medium Dependent Interface) (iv) supports an end user process and performs required file transfer.

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

Question 19 of 61

19. Question

The Hamming distance between 001111 and 010011 is

1
2
3
4

Question 20 of 61

20. Question

BSC is a

character oriented protocol
bit-oriented protocol
full-duplex protocol
half-duplex protocol

Question 21 of 61

21. Question

HDLC is

bit oriented
code transparent
code dependent
none of the above

Question 22 of 61

22. Question

Bit stuffing refers to

inserting a '0' in user data stream to differentiate it with a flag
inserting a '0' in flag stream to avoid ambiguity
appending a nibble to the flag sequence
appending a nibble to the user data stream

Question 23 of 61

23. Question

Choose the correct statement(s).

Baseband network uses analog technology.
Baseband network is Time Division Multiplaxed.
Broadband network uses digital technology.
In broadband network, the carrier signals operate at lower frequency.

Question 24 of 61

24. Question

In Ethernet CSMS/CD, the special bit sequence transmitted by media access management for collision handling is called as

preamble
postamble
jam
none of the above

Question 25 of 61

25. Question

Adaptive or dynamic directory used in packet routing changes

within each user session
with each user session
at system generation time only
both (a) and (b)

Question 26 of 61

26. Question

The method of network routing where every possible path between transmitting and receiving DTE is used is called

random routing
packet flooding
directory routing
message switching

Question 27 of 61

27. Question

Which one of the following network uses dynamic or adaptive routing?

TYMNET
ARPANET
SNA (IBM's System Network Architecture)
None of the above

Question 28 of 61

28. Question

The number of cross point needed for 10 lines in a cross point switch which is full duplex in nature and there are no self connection is

100
45
50
90

Question 29 of 61

29. Question

A terminal multiplexer has six 1200 bps terminals and ‘n’ 300 bps terminals connected to it. The outgoing line is 9600 bps. What is the maximum value of n?

4
16
8
28

Question 30 of 61

30. Question

The difference between a multiplexer and a statistical multiplexer is:

Multiplexer use TDM (time division multiplexing), while statistical multiplexer use FDM (frequency division multiplexing).
Multiplexers often waster the output link capacity, while statistical multiplexers optimize its use.
Statistical multiplexers need buffers while multiplexers do not need buffers.
Multiplexers use the X.25 protocol, while statistical multiplexers use the ALOHA protocol.

Question 31 of 61

31. Question

A modem constellation diagram has data points at (0,1) and (0,2) What type of modulation does the modem use?

phase modulation
Amplitude modulation
Both (a) and (b)
None of the above

Question 32 of 61

32. Question

Write the differential Manchester code for the given sketch

111100101
100010111
101001111
101001101

Question 33 of 61

33. Question

Maximum data rate of a channel for a noiseless 3-kHz binary channel is

300 bps
6000 bps
1500 bps
none of the above

Question 34 of 61

34. Question

The maximum data rate of a channelof 3000-Hz bandwidth and SNR of 30 dB is

15,000 bps
60,000 bps
30,000 bps
3,000 bps

Question 35 of 61

35. Question

In time division switches if each memory access takes 100 ns and one frame period is 125 μs, then the maximum number of lines that can be supported is

625 lines
1250 lines
2300 lines
318 lines

Question 36 of 61

36. Question

If the bit string 0111101111101111110 is subjected to bit stuffing for the flag string 01111110, the output string is

011110111110011111010
01111011111011111100
01111011111011111010
0111101111101111110

Question 37 of 61

37. Question

End-to-end connectivity is provided from host-to-host in

the network layer
the transport layer
the session layer
it is a combined functionality of the network and the data link layer.

Question 38 of 61

38. Question

Pick the correct statements.

In connection-oriented service, the destination address is to be specified only during the setup.
Initial setup is not possible in connectionless service
Packet sequencing is not guaranteed in connection-oriented service.
Initial setup is required for connectionless service.

Question 39 of 61

39. Question

The entry for NN if FD is node B is

E
C
G
none of the above

Question 40 of 61

40. Question

The entry of OD for the above case is

6
14
4
3

Question 41 of 61

41. Question

The OD if FD is node A is

6
9
13
7

Question 42 of 61

42. Question

Pick the correct statements about flooding.

It is a type of isolated routing.
It is a method in which every incoming packet is sent out on every outgoing line except the one by which it arrived.
Flooding does not always select the shortest path
Selective flooding is a type in which the packets are sent to those lines that are going approximately in the right direction

Question 43 of 61

43. Question

The parameter which gives the probability of the transport layer itself spontaneously terminating a connection due to internal problems is called

Protection
resilience
option negotiation
transfer failure

Question 44 of 61

44. Question

The ____ measures the number of lost of garbled messages as a fraction of the total sent in the sampling pariod.

Residual Error rate
Transfer failure porbability
Connection release failure probability
connection establishment failure probability

Question 45 of 61

45. Question

In session layer, during data transfer, the data stream responsible for the control purpose (i.e control of the session layer itself) is

regular data
typed data
capability data
expedited data

Question 46 of 61

46. Question

The minimum number of bits required to represent B is

1
2
3
4

Question 47 of 61

47. Question

The minimum number of bits required to represent all the symbols together is

14
11
12
15

Question 48 of 61

48. Question

The average code length of the given problem is

2
2.25
2.45
3

Question 49 of 61

49. Question

In cryptography, the following uses transposition ciphers and the keyword is LAYER. Encrypt the following message. (Space are omitted during encryption)
WELCOME TO NETWORK SECURITY!

WMEKREETSILTWETCOOCYONRU!
EETSICOOCYWMEKRONRU!LTWET
LTWETONRU!WMEKRCOOCCYEETSI
ONRU!COOCYLTWETEETSIWMEKR

Question 50 of 61

50. Question

Encrypt NEKEWNINRROGTTI using the above keyword in Transposition cipher method.

INTERWORKINGNET
INTERNETWORKING
WORKINGINTERNET
None of the above

Question 51 of 61

51. Question

Assuming that for a given network layer implementation, connection establishment overhead is 100 bytes and disconnection overhead is 28 bytes. What would be the minimum size of a packet the transport layer needs to keep up, if it wishes to implement a datagram service above the network layer and needs to keep its overhead to a maximum of 12.5%, (Ignore transport layer overhead)

512 bytes
786 bytes
1152 bytes
1024 bytes

Question 52 of 61

52. Question

Which of the following is not a standard RS-232C signal?

RTS
CTS
DSR
VDR

Question 53 of 61

53. Question

A high speed communication equipment typically would not be needed for

E-mail
transferring larger volume of data
supporting communication between nodes in a LAN
all of the above

Question 54 of 61

54. Question

Which of the following ISO level is more closely related to the physical communications facilities?

Application
Sesssion
Network
Data link

Question 55 of 61

55. Question

Which of the following is not a field in the Ethernet message packet?

Type
Data
Pin-code
Address

Question 56 of 61

56. Question

The network topology that supports bi-directional links between each possible nodes is

ring
star
tree
mesh

Question 57 of 61

57. Question

In a broad sense, a railway track is an example of

simplex
half-duplex
full-duplex
all of the above

Question 58 of 61

58. Question

The frequency range at which the land coaxial cables will be used is

10⁶ to 10⁸ Hz
10¹⁰ to 10¹¹ Hz
10³ to 10⁴ Hz
10¹⁴ to 10¹⁵ Hz

Question 59 of 61

59. Question

If the data rate of ring is 20 Mbps, signal propagation speed is 200 m/μ then the number of bits that can be placed on the channel of 200 km is

2,000 bits
20,000 bits
1,000 bits
none of the above

Question 60 of 61

60. Question

ICI (interface control information) is

used to transfer use data from layer to layer
used to exchange information by peer entities at different sites on the network to instruct an entity to perform a service funciton
a combination of service data unit (SDU) and protocol control information (PCI)
a temporary parameter passed between N and N - 1 layers to involve service functions between two layers

Question 61 of 61

61. Question

Match the following
1) Data link layer (i) the lowest layer whose function is to activate, deactivate and maintain the circuit between DTE and, DCE

2) Physical layer (ii) performs routing and communication

3) Presentation layer (iii) detection and recovery from errors in the transmitted data

4) Network layer (iv) Provides for the syntax of the data

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