How might you confirm the presence of a hidden node on the network?

How might you confirm the presence of a hidden node on the network?

• A. Turn on the request to send/clear to send (RTS/CTS) protocol and watch for increased network data throughput.
• B. Observe the signal strength from the AP on each client.
• C. Check the MAC address table in the AP.
• D. Disable RTS/CTS and see if throughput increases.

Answer: (A)

Hidden nodes happen when two devices can talk to the access point but cannot hear each other, so their transmissions can collide at the AP. RTS/CTS creates a short handshake before data is sent, reserving the channel and preventing simultaneous transmissions that could collide due to those hidden nodes. If you turn on RTS/CTS and you observe a noticeable increase in throughput, that improvement signals that collisions were happening because of hidden nodes, confirming their presence. The other ideas don’t reliably indicate hidden nodes. Signal strength from the AP on each client doesn’t reveal whether two clients can’t hear each other. The AP’s MAC address table shows who is connected, not whether those clients can overhear one another. Disabling RTS/CTS and seeing throughput increase would suggest RTS/CTS overhead was hurting performance (or that there wasn’t a hidden-node problem), not provide evidence of hidden nodes.

Hidden nodes happen when two devices can talk to the access point but cannot hear each other, so their transmissions can collide at the AP. RTS/CTS creates a short handshake before data is sent, reserving the channel and preventing simultaneous transmissions that could collide due to those hidden nodes. If you turn on RTS/CTS and you observe a noticeable increase in throughput, that improvement signals that collisions were happening because of hidden nodes, confirming their presence.

The other ideas don’t reliably indicate hidden nodes. Signal strength from the AP on each client doesn’t reveal whether two clients can’t hear each other. The AP’s MAC address table shows who is connected, not whether those clients can overhear one another. Disabling RTS/CTS and seeing throughput increase would suggest RTS/CTS overhead was hurting performance (or that there wasn’t a hidden-node problem), not provide evidence of hidden nodes.