A Cisco ACI fabric with an ARP packet must ensure detection of silent hosts with an ARP packet. The current bridge domain is configured with hardware proxy and unicast routing. Which step must be take

Setting Optimized Flood for L3 Unknown Multicast applies to Layer 3 multicast traffic, not the Layer 2 broadcast ARP packets used for silent host detection.

Enabling Flood for Multi Destination Flooding is a broader setting for broadcast, unknown unicast, and multicast, but ARP Flooding is the specific setting required for ARP-based silent host detection.

Setting L2 Unknown Unicast to Flood handles unknown destination MAC addresses for unicast frames, which is not directly responsible for the initial ARP broadcast-based detection of silent hosts.

Enabling ARP Flooding in the bridge domain is crucial because, even with hardware proxy and unicast routing, the fabric needs to flood ARP requests to learn the MAC addresses of silent hosts when their MAC-IP mapping is unknown. This allows ACI to glean the MAC address from the host's ARP response, completing the detection process.