A FlexPod Datacenter solution integrated with Cisco Application Centric Infrastructure (ACI) has distinct architectural requirements compared to a standard NX-OS design. First, the ACI fabric is fundamentally built on a leaf-spine network topology using Cisco Nexus 9000 Series switches. This design provides predictable, low-latency, non-blocking performance. Second, the ACI fabric is managed by a cluster of Cisco Application Policy Infrastructure Controllers (APICs). For a production environment, a minimum of three APICs is required to ensure high availability and maintain quorum in the event of a controller failure. These two requirements—a leaf-spine topology and a three-node APIC cluster—are specific additions for an ACI-based FlexPod solution.

A. A two-APIC cluster is not a supported configuration for a production environment because it cannot achieve quorum if one controller fails, leading to a read-only fabric state.

B. A core-edge topology is characteristic of traditional network designs, not the leaf-spine architecture that is mandatory for a Cisco ACI fabric.

1. Cisco and NetApp. (2021). FlexPod Datacenter with Cisco ACI and VMware vSphere 7.0 with NetApp ONTAP 9.8 Design Guide (CVD).

Page 21, "Cisco ACI Fabric": "The Cisco ACI fabric is built on a spine-leaf, two-tier network topology..." This supports the requirement for a leaf-spine topology (Answer C).

Page 22, "Cisco Application Policy Infrastructure Controller (APIC)": "The recommended minimum number of APIC appliances for a production ACI fabric is three. For smaller fabrics, a single APIC can be used for testing, PoC or lab purposes, but this is not a recommended configuration for production." This confirms the requirement for three APICs in a production solution (Answer D) and invalidates the two-APIC option (Answer A).

2. Cisco. (2022). Cisco Application Centric Infrastructure (ACI) Design Guide.

Chapter: ACI Fabric Infrastructure, Section: ACI Fabric Topology: "The ACI fabric is a leaf-and-spine design..." This reinforces the mandatory leaf-spine architecture (Answer C) and contradicts the core-edge model (Answer B).

Chapter: APIC Cluster, Section: APIC Cluster Connectivity and Operation: "A production ACI fabric is managed by a cluster of at least three APIC controllers." This document explicitly states the minimum supported cluster size for production is three (Answer D).