Computer Networks - Data Communication & Network Security


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?


1.0 x 105 microns


2 x 105 microns


2.5 x 105 microns


5 x 105 microns


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



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

Option: C

Explanation :


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

Option: B

Explanation :


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

Option: A

Explanation :


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

Option: A

Explanation :

Suggest an improvement