CWNA-109 Exam Dumps : Certified Wireless Network Administrator

The CWNA Official Study Guide (CWNA-109), Chapter 8: Troubleshooting and Spectrum Analysis, explains that hidden node problems occur when two or more client stations cannot hear each other but can both communicate with the same access point. This leads to collisions at the AP because the clients transmit simultaneously without sensing each other’s signals.

“Hidden node problems can often be identified in a protocol analyzer by observing excessive retransmissions from specific client stations. These retransmissions occur because the station’s frames are not acknowledged due to collisions caused by other stations that the transmitter cannot hear.”

— CWNA-108 Study Guide, Chapter 8, Hidden Node Problem Analysis, p. 393–395

Therefore, when analyzing for a hidden node issue, you will typically observe:

Retransmitted frames from multiple STAs.

Higher retry counts for affected stations compared to others.

Hence, the correct answer is C. Retransmitted frames from multiple STAs with higher retry counts than other STAs.

MU-MIMO capabilities of the bridges are not a factor considered when calculating the Link Budget for an outdoor point-to-point WLAN bridge link. The Link Budget is a calculation of the expected signal strength at the receiver based on various factors that affect the RF transmission. Some of these factors are operating frequency, transmit power, receive antenna gain, free space path loss, cable loss, connector loss, and environmental loss. MU-MIMO stands for Multi-User Multiple Input Multiple Output, which is a technology that allows multiple devices to communicate simultaneously using multiple spatial streams. MU-MIMO is not relevant for a point-to-point link, where there are only two devices involved. References: 1, Chapter 2, page 59; 2, Section 2.2