The MX9116n FSE has two single-density QSFP28 port groups, and the default setting for these two ports is 1x 100GbE. What other Ethernet breakout configurations are supported?

Question

Options

• A4x 10GbE
• B4x 10GbE
• C4x 10GbE
• D4x 16 Gb

• B
  92% (22)
• C
  4% (1)
• D
  4% (1)

Explanation

Note: This question appears to have a formatting issue - options A, B, and C all display as "4x 10GbE," which likely means the original choices were distinct but rendered incorrectly here (possibly A = 4x 25GbE, B = 4x 10GbE, C = 2x 50GbE, or similar). The analysis below treats B as the intended correct Ethernet breakout option.

Option B is correct because QSFP28 ports (which carry 100GbE by default) support Ethernet-based breakout configurations, and 4x 10GbE is a valid breakout using a QSFP28-to-4xSFP+ breakout cable, splitting the 100G port into four 10G lanes. Option D (4x 16 Gb) is wrong because 16 Gb is a Fibre Channel speed (16GFC), not an Ethernet standard - mixing FC nomenclature with Ethernet breakouts is a classic distractor on networking exams. Options A and C, if indeed identical to B in the source question, are likely wrong due to subtle differences in port density, mode compatibility, or configuration support that the original question intended to test.

Memory tip: For QSFP28 ports, think "100G = 4 lanes × 25G" natively, and Ethernet breakouts stay in the Ethernet family (10G, 25G, 50G) - any "16 Gb" answer on a breakout question is signaling Fibre Channel, not Ethernet, and should be eliminated immediately.

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