Your Layer 2 network uses 802.

This question focuses on port security and preventing " rogue switches " or multiple devices from accessing a single physical port simultaneously.

Single-Secure Supplicant Mode (Option A): This is the most restrictive 802.1X mode in Junos OS. It allows exactly one MAC address to be authenticated on the port at a time. If a device successfully authenticates, the switch will drop any traffic coming from any other MAC address on that same physical interface. If a user tries to plug in a switch, only the first device that authenticates will have access; all other devices behind that switch will be blocked.

Single Supplicant Mode (Option C): This mode allows the first authenticated user to " open " the port for all other users. This would actually allow a rogue switch to function once the first device is authorized.

Multiple Supplicant Mode (Option B): This allows multiple devices to connect, provided each one authenticates individually. While secure, it does not prevent a user from connecting multiple devices to the port, which violates the requirement to allow only one.

MAC-RADIUS (Option D): This is an authentication method, not a port-access mode that limits the number of supplicants.