When designing wireless networks, one strategy to consider is implementing security mechanisms at all layers of the OSI model. Which of the following protection mechanisms would protect layer 1?

Hardening applications is a Layer 7 (Application layer) control that addresses software vulnerabilities, not the physical RF transmission used by wireless networks.

Layer 1 of the OSI model governs the physical medium, which in wireless networks is the radio frequency signal broadcast through the air. Limiting RF coverage - through reduced transmit power, directional antennas, or physical shielding - prevents unauthorized clients from even receiving the signal, addressing security at the Physical layer. This is the only option that controls the physical medium rather than the data carried on it.

Firewalls operate at Layers 3 and 4 (Network and Transport) by filtering IP packets and port-based traffic, which is far above the Physical layer where RF signals exist.

Encryption such as WPA2/WPA3 operates at Layer 2 (Data Link) or higher, protecting the contents of transmitted frames but not controlling the physical reach or existence of the RF signal itself.