The scenario involves an application (App_1) on server S1 and a silent host application (App_2) on S2, both using the same VLAN encapsulation. The task is to force the ACI fabric to learn App_2 on Leaf-2. A silent host does not generate traffic, so special handling is needed.
Requirement Analysis
A silent host requires flooding (e.g., ARP or unknown unicast) to be learned by the fabric when it moves or is detected.
The goal is to ensure Leaf-2 learns App_2’s endpoint.
Option Evaluation
A. Set Multi-Destination Flooding to Drop:
Dropping multi-destination traffic prevents learning, which is counterproductive for a silent host.
[: Cisco ACI Bridge Domain Configuration Guide., B. Set Unicast Routing to Hardware Proxy: , Hardware proxy optimizes unicast routing but does not force learning of a silent host via flooding., Reference: Cisco ACI Routing Configuration Guide., C. Set L2 Unknown Unicast to Flood: , Enabling L2 unknown unicast flooding causes the fabric to flood traffic (e.g., ARP) across the bridge domain, allowing Leaf-2 to learn App_2’s MAC address even if it is silent., Reference: Cisco APIC Bridge Domain Settings, "L2 Unknown Unicast Flooding.", D. Set L3 Unknown Multicast to Optimized Flood: , This applies to multicast traffic and is irrelevant for learning a silent host’s MAC address., Reference: Cisco ACI Multicast Configuration Guide., Final Answer Justification, C is correct because flooding L2 unknown unicast traffic ensures the ACI fabric learns App_2 on Leaf-2 by propagating ARP or other discovery traffic., Primary Cisco References: , Cisco ACI Endpoint Learning Guide, "Flooding for Silent Hosts.", Cisco APIC Bridge Domain Configuration Guide., , ]
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