# Computer Networks - Data Communication & Network Security

71:

In which routing method do all the routers have a common database ?

 A. Distance vector B. Link state C. Link vector D. None of these Answer Report Discuss Option: B Explanation : In link state routing each router creates its own link state packet (LSP). Every other router receives this LSP through the flooding process. All routers therefore have the same information. This is compiled into the link state database.  Click on Discuss to view users comments. Write your comments here:
72:

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

 A. 4 B. 16 C. 8 D. 28 Answer Report Discuss Option: C Explanation : Click on Discuss to view users comments. Write your comments here:
73:

Data link layer retransmits the damaged frames in most networks. If probability of a frame's being damaged is p, then what is the mean number of transmissions required to send a frame if acknowledgements are never lost ?

 A. K / K - P B. 1 / K - P C. K / K(1 + p) D. p / K + 1 Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
74:

If a designer wants to design a point-to-point subnetwork with 10 routers of full duplex line, then total number of lines among them would be

 A. 10 B. 20 C. 45 D. 90 Answer Report Discuss Option: D Explanation : p> Full duplex  means transmission and reception can take place simultaneously. So we need 1 line for transmission and 1 for reception. that means between any 2 devices there will be 2 lines. So Number  of connections 10C2 = 45 Number  of lines required will be =  45*2=90   Click on Discuss to view users comments. Write your comments here:
75:

Maximum data rate of a noiseless 4 kHz channel using T1 PCM system is

 A. 32 kbps B. 56 kbps C. 80 kbps D. 24 kbps Answer Report Discuss Option: B Explanation : In this case 8000 samples/sec  are possible.  With T1, 7 bits are sent per per sample.  The  data rate is56 kbps. Click on Discuss to view users comments. Write your comments here: