CWNA Quality Control & Assurance 3

Question 1

An enterprise WLAN shows high retry rates (>20%) across multiple APs. Which condition MOST likely explains this?

Accepted Answer

Co-channel interference causing frame collisions

Answer

Co-channel interference causes multiple devices to transmit simultaneously, resulting in collisions that require frame retransmission and drive up retry rates.

Question 2

A wireless QA test reveals that roaming latency between APs exceeds 300 ms, disrupting VoIP calls. Which 802.11 amendment is specifically designed to reduce roaming latency?

Accepted Answer

802.11r (Fast BSS Transition)

Answer

802.11r pre-caches PMK key material between APs so clients can complete the four-way handshake faster during roaming, reducing handoff latency.

Question 3

During a wireless audit, an engineer discovers hidden nodes causing throughput degradation. Which 802.11 mechanism addresses hidden node problems?

Accepted Answer

RTS/CTS handshake

Answer

RTS/CTS causes stations to reserve the medium before transmitting, so hidden nodes that cannot hear each other are made aware of ongoing transmissions through CTS frames.

Question 4

A network QA team measures per-AP airtime fairness and finds legacy 802.11b clients at 1 Mbps are consuming disproportionate airtime. What is the recommended corrective action?

Accepted Answer

Enable minimum basic rate of 11 Mbps or higher to disassociate legacy clients

Answer

Raising the minimum basic rate excludes clients that cannot support faster rates, preventing slow legacy devices from monopolizing airtime.

Question 5

Which tool provides the MOST detailed information about non-802.11 RF interference in a specific frequency band?

Accepted Answer

Spectrum analyzer

Answer

A spectrum analyzer displays raw RF energy across frequencies regardless of source, allowing identification of non-802.11 interferers that packet analyzers cannot decode.

CWNA - Wireless Network Administrator Practice Test

CWNA - Wireless Network Administrator Practice Test

CWNA Quality Control & Assurance 3