What roaming technology uses stored keys at the APs for roam back if a client STA returns after having roamed away?

The correct answer is based on the concept of a method that enables client devices to quickly re-establish a connection with a wireless network after roaming away. PMK caching stands for Pairwise Master Key caching.

When a client fails over to another access point (AP), it typically needs to go through a full authentication process again when it returns to the original AP. However, with PMK caching, the original AP stores the Pairwise Master Key (PMK) associated with a client. This allows the client to re-authenticate without performing a full authentication handshake when it returns.

This technology becomes especially beneficial in environments where clients frequently move between different APs. By caching the PMK, the original AP can use this key to help the client re-establish its session faster and with less overhead. This leads to improved connectivity and a smoother user experience since the roaming process is expedited.

Other choices relate to roaming technologies but do not specifically use stored keys in the manner described. For instance, OKC (Optimized Key Caching) reduces the time it takes to re-establish connection by leveraging a similar concept but focuses on reducing the authentication burden in conjunction with a central controller rather than individual APs. Preauthentication refers to an authentication process that occurs