Which two statements about when the ARP request/response is not set to flooding on an Cisco ACI Fabric are true? (Choose two.)

Question

Options

• AStatic endpoint entries can be configured under the Tenant Networking section of the Cisco ACI UI for silent hosts to communicate with each other.
• BWhen the ARP originator and ARP target are known to the proxy, forwarding can no longer occur using the proxy because the source and destination are now known.
• CWhen an ARP target device responds, a response is sent to the proxy, which has an entry (or the ARP originator, so it is then forwarded to the leaf where ARP originator resides.
• DWhen ARP response is known by the proxy, the ARP is forwarded from the leaf that received the ARP to the spine, and onto the leaf where the ARP target resides.
• EThe proxy age time has no limit if the target of the ARP has not sourced a frame for some lime, the entry remains indefinite because this IS the only way forwarding can work between silent hosts.

• A
  21% (8)
• B
  8% (3)
• C
  67% (26)
• D
  5% (2)

Explanation

In Cisco ACI's ARP proxy mode (no flooding), C is correct because it accurately describes the ARP response path: the target sends its ARP reply to the spine proxy, which holds an entry for the originator and unicast-forwards that reply to the correct leaf - this is the core of proxy-based ARP. E is correct because silent hosts (those that never originate traffic) will never refresh their proxy entries, so the proxy age timer must be indefinite; if the entry expired, there would be no way to reach them without flooding.

Why the distractors are wrong:

• A is wrong because static endpoint entries for silent hosts are configured at the EPG level (under Application Profiles), not under the generic "Tenant Networking" section - the UI location is incorrect.
• B is wrong because it inverts the logic: when both endpoints are known to the proxy, forwarding becomes more efficient via unicast through the proxy, not impossible.
• D confuses the ARP request and response paths and incorrectly states the proxy forwards to "the ARP target's leaf" during the response phase - the target already sent the response; the proxy routes it back to the originator's leaf.

Memory tip: Think "C = Correct Return Path, E = Eternal Entry" - C describes the reply going back through the proxy to the originator, and E reminds you silent hosts need entries that never expire.

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