Which of the following is a major difference between 802.11 wireless and 802.3 Ethernet?

Question

Options

• A802.11 exclusively uses fiber optics for connectivity
• B802.3 supports dynamic frequency selection, while 802.11 does not
• C802.3 requires routing for all traffic between devices
• D802.11 uses CSMA/CA, whereas 802.3 uses CSMA/CD

• A
  3% (1)
• B
  7% (2)
• C
  3% (1)
• D
  86% (25)

Explanation

802.11 (Wi-Fi) uses CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance), while 802.3 (Ethernet) uses CSMA/CD (Collision Detection) - this is a fundamental architectural difference driven by the medium: wireless signals can't reliably detect collisions as they happen, so Wi-Fi tries to avoid them beforehand (via random backoff and acknowledgments), whereas wired Ethernet can detect a collision mid-transmission and stop immediately.

Why the distractors are wrong:

• A is false - 802.11 uses radio frequencies (2.4 GHz / 5 GHz / 6 GHz), not fiber optics; fiber is associated with wired standards like 802.3z.
• B is reversed - Dynamic Frequency Selection (DFS) is an 802.11 feature (used to avoid radar interference), not 802.3.
• C is false - 802.3 devices on the same LAN segment communicate directly via MAC addresses with no routing required; routing is a Layer 3 concern, not inherent to 802.3.

Memory tip: Think CA = Can't see collisions (wireless is "blind" to them, so it avoids them) vs. CD = Can Detect (wired Ethernet "sees" the collision on the cable and reacts). The medium determines the method.

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