Classical

Computer Networks - Data Communication & Network Security

26:  

 In which circuit switching, delivery of data is delayed because data must be stored and retrieved from RAM 

A. space-division
B. time-division
C. virtual
D. packet
 
 

Option: B

Explanation :
TSI (Time Slot Interchanger) in time division switches consists of random access memory (RAM) with several memory locations. The RAM ills up with incoming data from the time slots in the order received. Hence in time division
switches deliver of data is delayed because data
must be stored and retrieved from RAM.


27:  

If a network designer wants to connect 5 routers as point-to-point simplex line, then total number of lines required would be

A.

5

B.

10

C.

20

D.

32

 
 

Option: B

Explanation :

If 1st router connect with  other 4 routers then total  for 1st=4  same as 2nd router connect with 3 routers  so total for 2nd=3 same as for 3rd router connect with 2 routers  so total =2 same as 4th router with 1  so total=1  so total simplex lines will be = 4+3+2+1=10. So answer is 'B'.


28:  

 To interface a computer terminal with a modem, required physical layer standard is

A. RS 424 - A
B. RS 232 - C
C. RS 449
D. Either (b) or (c)
 
 

Option: D

Explanation :


29:  

 A 100 km long cable runs at the T1 data rate. The propagation speed in the cable is half the speed of light. How many bits is in the cable ?

A.

572

B.

672

C.

772

D.

873

 
 

Option: C

Explanation :

Propagation speed in the cable = 200,000 km/sec = 200 km/psec. Hence 100 km cable will be filled in 500 psec. This corresponds to four 193-bit frames, or 772 bits on the cable.


30:  

How much bandwith is there in 0.1 micron of spectrum at a wavelength of 1 micron ?

A.

20,000 GHz

B.

25,000 GHz

C.

30,000 GHz

D.

None of these

 
 

Option: C

Explanation :

Given : ∆ λ= 10-6, and   λ= 10-6

∆f = (c∆λ)/λ2=30,000 GHz




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