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# Computer Networks - Data Communication & Network Security

66:

Which of the following decides the role (sender or receiver) of a device on a network ?

 A. Line connection B. Link connection C. Line discipline D. Link decision Answer Report Discuss Option: C Explanation : Line discipline co-ordinate the link system. It determines which device can send and when it can send. Line discipline decides the role of a device on a network.  Click on Discuss to view users comments. Write your comments here:
67:

For stop-and-wait flow control, for n data packets sent, how many acknowledgments are needed ?

 A. n B. n-1 C. 2n D. n + 1 Answer Report Discuss Option: A Explanation : For stop-and-wait flow control for n data packets sent, in acknowledgements are needed. Click on Discuss to view users comments. Write your comments here:
68:

The collision domain of tranditional Ethernet and Fast Ethernet respectively are

 A. 250m, 250m B. 250m, 2500m C. 2500m, 250m D. 2500m, 2500m Answer Report Discuss Option: C Explanation : Click on Discuss to view users comments. Write your comments here:
69:

In a crossbar with 1000 crosspoints, how many statistically are in use at any time ?

 A. 100 B. 250 C. 500 D. 1000 Answer Report Discuss Option: B Explanation : A crossbar switch connects n inputs to m outputs in a grid, using electronic micro switches at each cross point, totally n x m cross points are required for crossbar switch. In general 25 percent of the cross points are used at a given time. The rest are idle so, totally 1000 cross points, so 25% = 250 crosspoint points are in use. Click on Discuss to view users comments. Write your comments here:
70:

Which of the following is a time - division switch?

 A. TSI B. TDM bus C. crosspoint D. both (a) and (b) Answer Report Discuss Option: D Explanation : In time division switch, slots are divided by time switching accomplished using time division multiplexing (TDM) and another device called time slot interchange (TSI). Click on Discuss to view users comments. Write your comments here:

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