010-151 · Question #70
Which two statements about the Ethernet media are true? (Choose two.)
The correct answer is A. A twisted-pair cable system has each pair of wires twisted together to reduce electromagnetic C. 40 Gigabit Ethernet twinax cables deploy Enhanced Quad Small Form Factor Pluggable (QSFP+). Twisted-pair wires are twisted to cancel EMI, and 40GbE twinax Direct Attach Copper cables use QSFP+ transceivers - both are accurate statements about Ethernet media.
Question
Which two statements about the Ethernet media are true? (Choose two.)
Options
- AA twisted-pair cable system has each pair of wires twisted together to reduce electromagnetic
- BCompared to multimode fiber, the single-mode fiber is designed for shorter distances with higher
- C40 Gigabit Ethernet twinax cables deploy Enhanced Quad Small Form Factor Pluggable (QSFP+)
- DThe twinax cables can be found in either a shielded twisted-pair or an unshielded twisted-pair
How the community answered
(56 responses)- A79% (44)
- B7% (4)
- D14% (8)
Why each option
Twisted-pair wires are twisted to cancel EMI, and 40GbE twinax Direct Attach Copper cables use QSFP+ transceivers - both are accurate statements about Ethernet media.
Twisting each wire pair causes external electromagnetic interference to induce equal and opposite noise on both conductors, which cancels out at the differential receiver - this is the fundamental noise-rejection mechanism that makes UTP and STP viable at high speeds.
This statement reverses the correct relationship - single-mode fiber supports far longer distances (up to tens of kilometers) than multimode fiber (limited to hundreds of meters) because its narrower 9-micron core eliminates modal dispersion.
40 Gigabit Ethernet twinax Direct Attach Copper cables are terminated with QSFP+ connectors, which multiplex four 10 Gb/s lanes to achieve 40 Gb/s aggregate throughput as specified in IEEE 802.3ba, making QSFP+ the correct and standard transceiver form factor for this media type.
Twinax cable is a balanced twin-conductor coaxial cable, not a form of twisted-pair; it cannot be categorized as either shielded twisted-pair (STP) or unshielded twisted-pair (UTP), which are entirely different cable constructions.
Concept tested: Ethernet media properties - twisted-pair EMI cancellation and 40GbE QSFP+ twinax
Source: https://standards.ieee.org/ieee/802.3ba/3847/
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