Quick Answer
The answer is leaf switch, spine switch, and APIC. These three components form the foundation of a Cisco ACI fabric, operating in a spine-leaf topology where every leaf switch connects to every spine switch in a full-mesh, non-blocking architecture. The spine switches handle all east-west traffic between leaf switches using IS-IS as the routing protocol for fabric discovery and forwarding, while the APIC serves as the centralized policy and management controller. On the ENCOR 350-401 exam, this question tests your understanding of the physical fabric building blocks, often appearing as a straightforward multiple-select item. A common trap is confusing the APIC with a data-plane device—remember, the APIC is purely a management plane controller and does not forward traffic. For a quick memory tip, think of the acronym “SLA” for Spine, Leaf, APIC, and recall that without any one of these three, the ACI fabric cannot function as designed.
This 350-401 practice question tests your understanding of virtualization. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE of the following are components of a Cisco ACI fabric? (Choose three.)
Firewall
Why wrong: Firewalls are external services, not part of ACI fabric.
Spine switch
Spine switches form the fabric backbone.
Router
Why wrong: Routing is integrated into leaf/spine, not a separate component.
APIC controller
APIC manages the ACI fabric.
Leaf switch
Leaf switches connect to endpoints.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Spine switch
The spine switch is a core component of a Cisco ACI fabric, forming the spine-leaf topology. Spine switches provide high-speed, non-blocking connectivity between leaf switches and handle all east-west traffic, relying on IS-IS as the routing protocol for fabric discovery and forwarding.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Firewall
Why it's wrong here
Firewalls are external services, not part of ACI fabric.
Spine switch
Why this is correct
Spine switches form the fabric backbone.
Related concept
Read the scenario before looking for a memorised answer.
Router
Why it's wrong here
Routing is integrated into leaf/spine, not a separate component.
APIC controller
Why this is correct
APIC manages the ACI fabric.
Related concept
Read the scenario before looking for a memorised answer.
Leaf switch
Why this is correct
Leaf switches connect to endpoints.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Cisco often tests the distinction between native fabric components (spine, leaf, APIC) and external devices (firewall, router) that can be integrated but are not part of the fabric itself, leading candidates to mistakenly include them as fabric components.
Detailed technical explanation
The ACI fabric uses a spine-leaf topology where all leaf switches connect to all spine switches in a full mesh, with no direct leaf-to-leaf connections. The fabric relies on the OpFlex protocol for policy enforcement and uses VXLAN encapsulation with MP-BGP EVPN for control plane distribution of endpoint information, ensuring scalable and efficient traffic forwarding.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the 350-401 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Virtualization — This question tests Virtualization — Read the scenario before looking for a memorised answer..
The correct answer is: Spine switch — The spine switch is a core component of a Cisco ACI fabric, forming the spine-leaf topology. Spine switches provide high-speed, non-blocking connectivity between leaf switches and handle all east-west traffic, relying on IS-IS as the routing protocol for fabric discovery and forwarding.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.
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