Which statement is true about 3-stage IP fabrics?

Question

Options

• AThere must be physical connections between all of the spine nodes.
• BEach leaf node must have at least one physical connection to each spine node.
• CThere must be physical connections between all of the leaf nodes.
• DEach leaf node must have at least two physical connections to each spine node.

• A
  3% (2)
• B
  71% (42)
• C
  7% (4)
• D
  19% (11)

Explanation

In a 3-stage IP fabric (leaf-spine), every leaf node must have at least one physical connection to every spine node - this guarantees that any leaf can reach any other leaf in exactly two hops (leaf → spine → leaf), providing full any-to-any connectivity without requiring direct leaf-to-leaf or spine-to-spine links.

A is wrong because spine nodes never connect directly to other spine nodes - that would add a 4th stage and violate the core design principle. C is wrong for the same reason applied to the access layer: leaf nodes connect only upward to spines, never laterally to other leaves. D is wrong because the architecture requires at least one connection per spine, not two; dual links per spine are an optional redundancy choice, not a structural requirement.

Memory tip: Picture a bipartite graph - leaves on the bottom, spines on top, with every bottom node wiring up to every top node, but zero horizontal wires on either row. "No siblings talk directly; everyone goes through the spine."

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