CWS CWS WLAN Troubleshooting 3

Question 1

What is the hidden node problem in a WLAN?

Accepted Answer

Two clients that can hear the AP but cannot hear each other, causing collisions at the AP

Answer

An AP that does not broadcast its SSID beacon

Answer

A client assigned a private IP hidden from the router

Answer

An AP using non-standard channel settings

Question 2

What is the effect of multipath propagation on WLAN performance?

Accepted Answer

Signal copies arriving at different times, causing inter-symbol interference and degraded throughput

Answer

Increased transmit power consumption by the AP

Answer

Improved coverage due to signal reflection off walls

Answer

Reduced adjacent channel interference in the environment

Question 3

A wireless client is experiencing slow roaming between APs. What is the most likely cause?

Accepted Answer

Client clinging to current AP despite poor signal (sticky client)

Answer

Too many SSIDs broadcast on the network

Answer

Beacon interval set too high on the APs

Answer

Mismatched VLAN assignments between APs

Question 4

Which 802.11 mechanism is designed to mitigate the hidden node problem?

Accepted Answer

RTS/CTS (Request to Send / Clear to Send)

Answer

MIMO spatial multiplexing

Answer

OFDM subcarrier spacing

Answer

Beamforming with MU-MIMO

Question 5

A spectrum analyzer shows a high-amplitude, frequency-hopping signal in the 2.4 GHz band. What is the most likely interference source?

Accepted Answer

Bluetooth device using FHSS

Answer

Neighboring Wi-Fi network on channel 6

Answer

Microwave oven leaking RF energy

Answer

ZigBee home automation sensor

Question 6

When troubleshooting a WLAN, what does the term 'noise floor' refer to?

Accepted Answer

The ambient level of background RF energy in the environment when no desired signals are present

Answer

The minimum SNR required for 802.11ac MCS index 0 operation

Answer

The maximum acceptable frame retry rate percentage

Answer

The signal level at which a client initiates a roaming scan

Question 7

What troubleshooting information does a WLAN controller provide that standalone APs cannot?

Accepted Answer

Centralized logging, client association history, and aggregate statistics across all managed APs

Answer

Raw RF spectrum data for each AP location

Answer

Physical layer error correction for 802.11ac frames

Answer

Dynamic IP address assignment for wireless clients