Certified Wireless Network Administrator (CWNA) Practice Test

Hidden nodes refer to devices in a wireless network that are not able to hear each other's transmissions due to distance or obstacles, leading to potential collisions when they attempt to communicate with a common access point simultaneously. In the context of the options provided, the presence of obstacles causing signal attenuation is a significant factor.

When obstacles, such as walls or furniture, are present, the signals from some devices may be weakened or completely blocked, preventing those devices from detecting each other’s signals. This means they cannot sense when the air is busy (i.e., when another device is transmitting). As a result, multiple devices may transmit at the same time, unaware that others are doing so, which increases the likelihood of data collisions.

Conversely, short-range connections limit the opportunity for hidden nodes since devices within close proximity are more likely able to detect each other's transmissions. Highly populated networks might create a busy environment, but they don't inherently lead to hidden node problems. Lastly, stable connection protocols generally help manage collisions rather than exacerbate them. Given this context, obstacles causing signal attenuation is indeed the cause that is most likely to increase collisions due to the hidden node issue.