How Do 802.11a and 802.11ac Clients Affect Wireless Network Design?
During a meeting to gather the requirements for a new Wi-Fi network design, the customer requests that 802.11a and 802.11ac clients be able to connect. Which affect does this have to the wireless network?
Community Votes
75% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
It tests whether you know that supporting legacy 802.11a clients alongside 802.11ac degrades WLAN throughput, and the trap is assuming that both being 5 GHz means the AP can simply use wider channels.
Mixing 802.11a and 802.11ac clients on the same 5 GHz WLAN is a classic 300-425 design trade-off: the legacy 54 Mbps generation drags overall throughput down. This page confirms B and explains why the wider-channel option is the trap.
Picking A — because 802.11a and 802.11ac both live in the 5 GHz band, candidates assume the AP can combine channels into bigger widths, but 802.11a is 20 MHz-only and its presence actually blocks channel bonding.
Community Discussion (3 comments)
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Expert Analysis
Why the Answer Is Correct
802.11a is a 5 GHz, 20 MHz-only technology that tops out at 54 Mbps, while 802.11ac reaches gigabit-class rates using 40/80/160 MHz channels, higher QAM and MU-MIMO. When a design requirement forces the WLAN to serve both generations, the AP must transmit to 802.11a clients at legacy rates, add legacy protection/coexistence overhead, and spend airtime on very slow frames — so the aggregate throughput available to everyone, including 802.11ac clients, drops. In a requirements-gathering meeting this is exactly the design consequence you should flag to the customer: requesting 802.11a support caps the performance of the new network. Option B, lower throughput, is therefore the correct effect.Why the Other Options Are Wrong
Option A, bigger channel width, is backwards: 802.11a cannot operate on 40/80 MHz channels, and the need to support 20 MHz-only clients constrains rather than expands the channel plan. Option C, 2.4 GHz signal congestion, is irrelevant because both 802.11a and 802.11ac operate exclusively in the 5 GHz band, so this requirement adds no load to 2.4 GHz spectrum. Option D, higher RF reflection, describes a physical-layer multipath/material phenomenon tied to the environment and mounting, not to which client generations are admitted to the SSID. Only B is a direct, causal consequence of the stated requirement.Community Comment Notes
Farhad123 argues the same path as this analysis, saying a mixed-generation network "means lower throughput" and pointing out that an 802.11a client consumes more air time for the same payload. Jonycici concurs with a terse "B. lower throughput". AdamNoe takes the distractor route, claiming "802.11a and 802.11ac works at 5GHz and can combine channels for bigger channel widths" — sharing a band does not let an AP bond 802.11a into wider channels, and 802.11a clients actively prevent 40/80 MHz use. The vote split (B: 75, A: 25) reflects that the band-coexistence misunderstanding is the main source of error.Exam Strategy
When an option set mixes a client-capability requirement with physical-layer answers (channel width, RF reflection, band congestion), ask what the requirement actually forces the AP to do at the airtime level. Legacy client support almost always resolves to throughput degradation, because the slowest supported rate sets the effective performance floor.
Frequently Asked Questions
Why doesn't mixing 802.11a and 802.11ac clients give bigger channel widths?
802.11a is limited to 20 MHz channels, so admitting those clients prevents the AP from using 40/80 MHz bonding for 802.11ac — the requirement restricts channel width rather than expanding it.
Why is 2.4 GHz signal congestion not the effect here?
Both 802.11a and 802.11ac operate only in the 5 GHz band, so adding these clients puts no additional load on the 2.4 GHz spectrum.