Which condition is not supported with an Elastic Scale High Availability mode?

Question

Options

• ABuffer Service Engines for high availability
• BAuto Scaling of Virtual Services
• CMaintaining original client source IP to the back-end server pool
• DLayer 3 / ECMP scale out

• A
  3% (1)
• B
  8% (3)
• C
  6% (2)
• D
  83% (30)

Explanation

Layer 3 / ECMP scale out (D) is not supported in Elastic Scale High Availability mode because this HA mode relies on Service Engine (SE)-based traffic distribution at the application layer, not network-layer routing. ECMP is a routing protocol mechanism that distributes traffic across equal-cost paths at Layer 3, which is architecturally incompatible with how Elastic Scale HA manages failover and load distribution through SEs.

Why the distractors are wrong:

• A is incorrect because Buffer SEs (the "M" in N+M HA) are a core feature of Elastic Scale HA, providing standby capacity without dedicated Active/Standby pairing.
• B is incorrect because Auto Scaling of Virtual Services across multiple SEs is precisely what Elastic Scale HA enables - it's the mode's primary purpose.
• C is incorrect because preserving the original client source IP to back-end servers is supported in Elastic Scale HA through proxy and non-proxy forwarding configurations.

Memory tip: Think of "Elastic Scale" as SE-managed scaling (Layer 4–7). L3/ECMP is a router-managed concept - if it belongs to the network routing table, it doesn't belong in Elastic Scale HA. The moment you see "L3" paired with "Elastic Scale HA," that's your signal something doesn't fit.

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