In computer networks, which of the following are the basic categories of…
2023
In computer networks, which of the following are the basic categories of communication channels (paths) when classified by data-transmission speed?
I. Narrow band
II. Voice band
III. Broad band
Answer: B. I, II and III — ConceptA communication channel can be classified by the amount of information it carries per unit time. In the traditional transmission-speed classification,…
- A.
Only I and II
- B.
I, II and III
- C.
Only II and III
- D.
Only I and III
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Correct answer: B
Concept
A communication channel can be classified by the amount of information it carries per unit time. In the traditional transmission-speed classification, the ranges progress from narrow band to voice band and then to broad band.
Application
Narrow-band channels represent the low-speed range.
Voice-band channels represent the ordinary voice-frequency or telephone-grade range used for data communication.
Broad-band channels represent the wider, higher-speed range.
Cross-check and contrast
Only I and II leaves out broad band, one of the speed-based categories.
Only II and III leaves out narrow band, the low-speed category.
Only I and III leaves out voice band, the telephone-grade category.
Simplex and duplex classify transmission direction, while twisted pair and fibre classify physical media; those are different classification axes.
Result
Therefore, the applicable statements are I, II and III.