An engineer must speed up the reauthentication delays that are being experienced on the wireless infrastructure by deploying a key-caching mechanism. Which mechanism must be configured?

PEAP is an EAP authentication method that encapsulates inner authentication inside a TLS tunnel - it is an authentication protocol, not a key-caching or fast-roaming mechanism.

Fast Transition (802.11r) uses a Mobility Domain and pre-establishes keying material between the client and target AP before the roam occurs, eliminating the full 802.1X/EAP exchange on every transition. The client caches the Pairwise Master Key Security Association (PMKSA) derived during the initial authentication and uses it to derive new PTKs for subsequent APs within the mobility domain. This dramatically reduces reauthentication latency compared to a full EAP round-trip.

PMF (Protected Management Frames, 802.11w) protects management frames such as deauthentication and disassociation from spoofing, and has no role in reducing reauthentication delays.

GTK-randomization generates a new Group Temporal Key after each client disassociation to prevent key-reuse attacks, and does not address reauthentication speed or key caching.