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# Computer Networks - Data Communication & Network Security

31:

It is desired to send a sequence of computer screen images over an optical fiber. The screen is 480 x 640 pixels, each pixel being 24 bits. There are 60 screen images per second. How much bandwidth is needed, and how many microns of wavelenth are needed for this band at 1.30 microns?

 A. 1.0 x 105 microns B. 2 x 105 microns C. 2.5 x 105 microns D. 5 x 105 microns Answer Report Discuss Option: C Explanation : Data rate is 480 x 640 x 24 x 60 bps, which is 442 Mbps. Assume 1 bps per Hz. ∆ λ  = 4.42 x 105 From the ralation  λ = ∆ λ c  ⇒ ∆ λ= λ2/c ∆ λ =4.42 x 105 λ=2.5 x 105 microns   Click on Discuss to view users comments. anshu said: (3:48am on Tuesday 3rd February 2015) 480 x 640 x 24 x 60 bps=442368000bps how it is 442 Mbps Write your comments here:
32:

Establishing a virtual connection is virtually equivalent to

 A. connecting as virtual memory B. physically connecting a DTE and DCE C. placing a telephone call prior to a conversion D. placing a modem prior to a conversion Answer Report Discuss Option: C Explanation : Click on Discuss to view users comments. Write your comments here:
33:

How many digits of the network user Address are known as the DNIC (Data Network Identiication Code) ?

 A. First three B. First four C. First five D. First seven Answer Report Discuss Option: B Explanation : Click on Discuss to view users comments. Write your comments here:
34:

How many digits of the DNICC (Data Network Identiication Code) identify the country ?

 A. First three B. First four C. First five D. First six Answer Report Discuss Option: A Explanation : Click on Discuss to view users comments. Write your comments here:
35:

Which of the following digits are known as the area code of the network user address (NUA) ?

 A. 5-7 B. 1-4 C. 8-12 D. 13-14 Answer Report Discuss Option: A Explanation : Click on Discuss to view users comments. Write your comments here:

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