350-601 Question #386: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. SVR-A in EPG-A/BD-A fails to reach SVR-B in EPG-B/BD-B. Which two conditions should be verified to analyze the traffic between the two EPGs? (Choose two.)

Options

• AA contract exists between EPG-A and EPG-B and allows the traffic.
• BLimit Endpoint Learning is disabled on the bridge domain for EPG-B.
• CSVR-B is learned as an endpoint in EPG-B from Node-112.
• DEPG-A and EPG-B are excluded from the preferred group.
• EThe bridge domain for EPG-B floods ARP packets.

Explanation

When two endpoints in different Endpoint Groups (EPGs) within Cisco ACI fail to communicate, it is crucial to verify the existence of a contract allowing traffic between those EPGs and confirm that both endpoints are correctly learned within their respective EPGs.

Common mistakes.

• B. Limit Endpoint Learning (also known as Unicast Routing) controls whether the Bridge Domain performs IP learning; disabling it would not directly prevent traffic, and it's generally enabled for IP routing.
• D. Whether EPG-A and EPG-B are excluded from a preferred group primarily affects contract enforcement within a VRF, not necessarily the fundamental ability of a contract to allow traffic.
• E. While ARP flooding is necessary for endpoints to learn each other's MAC addresses within the same broadcast domain, this is an underlying mechanism; the primary issues for inter-EPG communication failure are typically contracts and endpoint learning.

Concept tested. Cisco ACI inter-EPG communication troubleshooting

Reference. https://www.cisco.com/c/en/us/td/docs/aci/apic/5x/troubleshooting/cisco-aci-troubleshooting-guide-50.html

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