Classical

Computer Networks - Data Communication & Network Security

61:  

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

A.

simplex

B.

half-duplex

C.

full-duplex 

D.

all of these

 
 

Option: B

Explanation :


62:  

Which of the following access control methods is probabilstic ?

A.

Polling

B.

Contention

C.

Token passing

D.

Sliding window

 
 

Option: D

Explanation :


63:  

 In stop-and-wait ARQ, if data 1 has an error, then receiver sends which frame ?

A.

NAK 0

B.

NAK 1

C.

NAK 2

D.

NAK

 
 

Option: D

Explanation :

Stop-and-wait ARQ (Automatic Repeat Request) is similar to stop - and - wait flow control protocol, but it includes retransmission of data in case of lost or damaged frames.
Both data and ACK frames are numbered alternately 0 and 1. But NAK frames are not numbered. If any error occurs the Receiver sends a NAK frame, it tells the sender to retransmit the frame last sent. Sender maintains a copy of frame until the Acknowledgement is back.


64:  

In which communication, poll/select method used to determine control of the line ?

A.

peer-to-peer

B.

peer-to-primary

C.

primary-to-peer

D.

primary-to-secondary

 
 

Option: D

Explanation :

Poll / select method is used in primary - to - secondary communication. ENQ/ACK is used in peer-to-peer communication method.


65:  

The secondary device in a multipoint configuration sends data in response to which of the following event ?

A.

ACK

B.

ENQ

C.

Poll

D.

Sel

 
 

Option: C

Explanation :

Poll/select is a line discipline method. The primary device always initiates communication with either a poll or select (SEL) frame. In this point the secondary device sends data in response to a poll frame event.




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