What Fiber Optic standard supports up to 400 Gbps

Question

Options

• ANo standard supports that bandwidth
• BQSFP+
• CQSFP28
• DQSFP-DD

• A
  2% (1)
• B
  5% (2)
• D
  93% (40)

Explanation

QSFP-DD (Quad Small Form-factor Pluggable Double Density) is correct because it was specifically designed to support 400 Gbps throughput by doubling the electrical interfaces of standard QSFP to 8 lanes, each capable of 50 Gbps - making it the go-to standard for 400G optical networking.

Why the distractors are wrong:

• A is incorrect - 400 Gbps is a real, standardized bandwidth supported by QSFP-DD hardware today.
• B (QSFP+) maxes out at 40 Gbps (4 lanes × 10 Gbps), making it two generations behind what's needed here.
• C (QSFP28) supports 100 Gbps (4 lanes × 25 Gbps), which is a common standard but still 4× short of 400 Gbps.

Memory tip: Think of the progression as a ladder - QSFP+ (40G) → QSFP28 (100G) → QSFP-DD (400G). The "DD" stands for Double Density, hinting at the doubled lane count that enables the massive bandwidth jump. If the question mentions 400G, the answer almost always ends in DD.

No community discussion yet for this question.