Classical

Computer Networks - Data Communication & Network Security

81:  

For a sliding window of size n-1 (n sequence numbers), there can be maximum of how many frames sent but unacknowledged ?

A.

0

B.

n -1

C.

N

D.

n +1

 
 

Option: B

Explanation :

In sliding window protocol, the window size is n 1, then its maximum capability is n - 1.


82:  

Select incorrect statement in error retransmission used in continuous ARQ method.

A.

Go-back-N method requires more storage at the receiving site

B.

Selective repeat involves complex login than GO-back-N

C.

Go-back-N has better line utilization

D.

Selective repeat has better line utilization

 
 

Option: C

Explanation :

Go-back-N has better line utilization is incorrect statement. Because if there is an error at the receiver the frames must be retransmitted where the error occurred in the transmission.

Option (A) statement is correct because  in Go- Back-N method  sometimes when acknowledgement is not received by sender then sender assumes that packet is not received by receiver so he again sends the packet. So receiver requires more memory to store. and option (C) statement is incorrect because if there is an error  at the receiver, the frames must be retransmitted where the error occured in the transmission. So, answer is 'C'.


83:  

Collision domain can be compared to which distance data travels between two stations ?

A.

Minimum

B.

Maximum

C.

Virtual

D.

Both (a) and (b)

 
 

Option: B

Explanation :


84:  

How many crosspoints are needed in a single-stage switch with 40 inputs and 50 outputs ?

A.

40

B.

90

C.

50

D.

2000

 
 

Option: D

Explanation :

In a single stage.switchn inputs and m outputs.
Totally n x m crosspoints are needed.
Here, n = 40 and m = 50
n x m =2000 


85:  

 In a time - division switch, which governs the destination of a packet stored in RAM?

A.

TDM bus

B.

Crosspoint

C.

crossbar

D.

Control unit

 
 

Option: D

Explanation :

In time division switch, based on the control unit decisions order of slots and destinations of a packet stored in RAM are governed.




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