MA5600 supports ADSL2+, which of the following descriptions about ADSL2+ is incorrect?

Question

Options

• AThe maximum downlink speed is 24Mbit/s
• BThe farthest reachable distance is 6.5km
• CUse high frequency bands, sub-channels (32-511) and sub-channels above 512.
• DThe spectrum bandwidth is 1.104MHz

• A
  9% (3)
• B
  3% (1)
• C
  17% (6)
• D
  71% (25)

Explanation

Option D is incorrect because ADSL2+ has a spectrum bandwidth of 2.208 MHz, not 1.104 MHz. The 1.104 MHz figure belongs to standard ADSL and ADSL2, which use sub-channels up to 255. ADSL2+ doubles this range by extending to sub-channels up to 511, which is precisely why it can achieve the higher speeds described in option A. Options A, B, and C are all accurate: the 24 Mbit/s maximum downlink speed and 6.5 km reach are defining characteristics of ADSL2+, and option C correctly describes its use of the extended downstream sub-channel range (32-511) plus higher bands.

Memory tip: The "2+" in ADSL2+ means it doubles the spectrum of ADSL2 -- from 1.104 MHz to 2.208 MHz. If you remember that doubling the sub-channels (256 to 512) also doubles the bandwidth, you will never confuse ADSL2+ with its predecessors on an exam.

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