What is the minimal number of operational Cisco APICs in a cluster that are needed to ensure that policy modification is still possible?

Question

Options

• A3
• B2
• C4
• D1

• A
  93% (51)
• B
  2% (1)
• C
  2% (1)
• D
  4% (2)

Explanation

A cluster of 3 APICs is the minimum size that guarantees policy modification remains available even when a node fails. Cisco's APIC cluster uses a quorum model - a majority of nodes must be healthy to permit write operations (policy changes). With 3 nodes, losing 1 still leaves 2 operational, which satisfies the majority quorum (2 of 3), keeping policy modification enabled.

Why the distractors are wrong:

• B (2): A 2-node cluster has no fault tolerance for writes - if one fails, you have only 50% of nodes, which does not meet quorum, so policy modification is blocked.
• D (1): A single APIC provides no redundancy; any failure eliminates all policy modification capability entirely.
• C (4): While valid in production for added resilience, 4 is not the minimum - 3 already satisfies the requirement.

Memory tip: Think "3 is the magic number" - it's the smallest odd number that allows majority quorum (2-of-3) to survive after a single failure. ACI clusters are always recommended in odd numbers (3, 5, 7) precisely for this quorum math.

No community discussion yet for this question.