At which layer does 802.11i provide authentication?

The choice of Layer 2 as the correct answer is based on the OSI model, where this layer is responsible for data link layer functionalities, including media access control and logical link control. The 802.11i standard is an amendment to the IEEE 802.11 wireless networking standard, enhancing WLAN security. It specifically addresses the need for robust authentication mechanisms.

In the context of wireless networking, authentication mechanisms such as those provided by WPA2 (Wi-Fi Protected Access 2) or WPA3 are implemented at Layer 2. This is critical because wireless communication typically involves devices negotiating their connection and confirming the validity of users before allowing network access. The EAP (Extensible Authentication Protocol) methods defined in 802.11i facilitate various forms of authentication, including passwords, certificates, or other credentials, all operating at this layer.

Such authentication is crucial to securing the connection before any data encapsulation takes place at higher layers, ensuring that only authorized devices can connect to the network and preventing potential threats from unauthorized access.