CCNA Network Infrastructure and Connectivity Practice Question
Exhibit
AP Name : AP9130-01 MAC Address : aabb.cc00.0100 Admin State : ENABLED Operational State : UP Channel Width : 80 MHz Channel : 36 DFS Status : DFS-NON-COMPLIANT Primary Channel : 36 Secondary Channel : 40 Radio Band : 5 GHz Client Count : 25 Utilization : 75% Interference : HIGH Power Level : 1 (Maximum) Antenna Type : Internal Antenna Gain : 4 dBi 802.11 Protocol : 802.11ac Beacon Interval : 100 TU DTIM Period : 2 Supported Data Rates : 6,9,12,18,24,36,48,54 Mbps MCS Rates : 0-9 (HT), 0-9 (VHT) QoS Parameters : WMM Enabled Security : WPA2-PSK Rogue Detection : Enabled
A network engineer is troubleshooting a wireless performance issue in a dense office environment. Clients on the 5 GHz band are experiencing low throughput even though they are close to the AP. The AP is a Cisco 9130AXI running IOS-XE 17.9. What is the most likely cause of the poor performance?
⚠ Common exam trap
Cisco often tests the misconception that wider channels always improve performance, when in reality, in dense environments, 80 MHz or 160 MHz channels cause severe interference and throughput degradation, especially with 802.11ac's lack of spatial reuse mechanisms.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The AP is operating in 802.11ac mode instead of 802.11ax, and the 80 MHz channel bonding is causing high interference in the dense environment.
In a dense office environment, using 80 MHz channel bonding with 802.11ac (Wave 2) increases the likelihood of co-channel interference and overlapping basic service sets (OBSS), which degrades throughput despite strong signal. The Cisco 9130AXI supports 802.11ax (Wi-Fi 6), which includes OFDMA and better spatial reuse, but if the AP is configured for 802.11ac mode, it loses these efficiency gains and suffers from the wide channel's interference penalty.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The AP is using an incorrect channel width of 80 MHz, which is not supported by 802.11ac.
Why it's wrong here
802.11ac explicitly defines channel bonding support for 80 MHz and even 160 MHz as optional, so an 80 MHz width is fully compliant with the standard. The real problem is that bonding to 80 MHz consumes a large contiguous slice of spectrum, and in a dense environment this increases the chances of overlapping basic service sets and co-channel interference. Therefore, the channel width is not unsupported; it is simply too wide for the RF environment, misidentifying the root cause.
- ✓
The AP is operating in 802.11ac mode instead of 802.11ax, and the 80 MHz channel bonding is causing high interference in the dense environment.
Why this is correct
The AP is running 802.11ac (Wi-Fi 5), which relies on OFDM and wide 80 MHz channels to achieve high peak rates, but in a dense deployment that wide channel exacerbates interference and medium contention. Migrating to 802.11ax (Wi-Fi 6) would use OFDMA to split the channel into resource units, letting multiple clients share the spectrum simultaneously and reducing collision overhead. The combination of a legacy PHY and an overly broad channel bond is exactly what degrades throughput here, making this the correct diagnosis.
- ✗
The AP has DFS non-compliance, which prevents it from using channel 36 and causes the radio to operate at reduced power.
Why it's wrong here
DFS non-compliance means the AP is not properly detecting radar, but it does not necessarily reduce power; it may cause the AP to avoid certain channels. The power level is set to maximum (1), so power reduction is not the issue.
- ✗
The AP is using WPA2-PSK instead of WPA3, which causes lower throughput due to weaker encryption.
Why it's wrong here
WPA2-PSK uses AES-CCMP for encryption, whose per-frame overhead is negligible and comparable to the AES-GCMP used by WPA3; neither cipher adds enough processing delay or header size to materially reduce throughput. Performance drops in dense environments are driven by RF layer issues such as interference, channel utilization, and retransmissions, not by the security handshake or encryption algorithm. Thus, attributing the problem to WPA2-PSK is technically unfounded and confuses security configuration with physical-layer capacity.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The AP is operating in 802.11ac mode instead of 802.11ax, and the 80 MHz channel bonding is causing high interference in the dense environment.Correct answer▾
Why this is correct
The AP is running 802.11ac (Wi-Fi 5), which relies on OFDM and wide 80 MHz channels to achieve high peak rates, but in a dense deployment that wide channel exacerbates interference and medium contention. Migrating to 802.11ax (Wi-Fi 6) would use OFDMA to split the channel into resource units, letting multiple clients share the spectrum simultaneously and reducing collision overhead. The combination of a legacy PHY and an overly broad channel bond is exactly what degrades throughput here, making this the correct diagnosis.
✗The AP is using an incorrect channel width of 80 MHz, which is not supported by 802.11ac.Wrong answer — click to see why▾
Why this is wrong here
802.11ac supports 80 MHz channel bonding, so this is not incorrect.
✗The AP has DFS non-compliance, which prevents it from using channel 36 and causes the radio to operate at reduced power.Wrong answer — click to see why▾
Why this is wrong here
DFS non-compliance does not directly reduce power; it may cause channel avoidance, but the power is set to maximum.
✗The AP is using WPA2-PSK instead of WPA3, which causes lower throughput due to weaker encryption.Wrong answer — click to see why▾
Why this is wrong here
WPA2-PSK does not cause throughput degradation; the issue is interference and protocol mode.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Go deeper
Related to this question
Learn chapter
Network Topology Types
Key term
Throughput
Throughput is the rate at which data is successfully transferred from one point to another over a network, typically measured in bits per second.
Key term
Wi-Fi
Wi-Fi is a technology that lets devices like laptops and phones connect to the internet or communicate with each other wirelessly using radio waves.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 200-301 exam.