Which two statements about Cisco ACI interaction with STP in legacy networks are true? (Choose two)

Question

Options

• AExternal switches ignore flooded BPDU frames received from the Cisco ACI fabric.
• BBPDU guard is enabled on FEV ports by default.
• CBPDU guard cannot be configured on leaf-edge ports.
• DSTP is enabled by default within the Cisco ACI fabric.
• EBPDU frame is flooded within EPG No configuration is required.

• A
  89% (17)
• B
  5% (1)
• E
  5% (1)

Explanation

Cisco ACI does not run STP internally - the fabric uses IS-IS and ECMP for loop prevention. However, it is STP-aware by default (D is correct): ACI handles BPDUs from connected legacy switches without requiring explicit STP configuration. When those BPDUs are flooded through the fabric, external switches treat the ACI fabric as a transparent pass-through device rather than a participating STP bridge, so they don't incorporate ACI into their STP topology calculations - they effectively ignore the flooded frames for STP purposes (A is correct).

Why the distractors are wrong:

• B - BPDU guard is not enabled by default on FEX ports; it must be explicitly configured.
• C - BPDU guard can be configured on leaf-edge ports (and is a recommended security practice).
• E - BPDUs are flooded within the EPG, but this is not zero-config; proper bridge domain and EPG configuration is still required for the behavior to function correctly.

Memory tip: Think "ACI = STP-Deaf Inside, STP-Aware Outside by Default." The fabric won't join your STP domain (so external switches ignore its flooding), but it ships ready to handle incoming BPDUs from legacy networks - no extra STP setup needed.

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