Which statement describes the relationship among the three Cisco layers?

• A. Access Layer connects to Distribution Layer, which connects to Core Layer
• B. Core Layer connects directly to Access Layer
• C. Distribution Layer connects only to external networks
• D. Access Layer includes edge routers

Answer: (A)

In Cisco's three-layer design, traffic moves from the Access layer to the Distribution layer and then to the Core layer. The Access layer connects end devices and uplinks to the Distribution layer, which aggregates traffic, enforces policies, and handles inter-VLAN routing. The Distribution layer then connects to the Core layer, the high-speed backbone that carries traffic across the network. This setup makes the described relationship correct: the Access Layer connects to the Distribution Layer, which connects to the Core Layer.

Why the other ideas don’t fit: connecting the Core directly to the Access layer bypasses the Distribution layer and its policy/routing functions, which is not typical for a three-tier design; saying the Distribution layer only connects to external networks ignores its role in connecting to the Access layer and to the Core; and the Access layer isn’t where edge routers belong—edge routers sit at the network boundary, while the Access layer focuses on connecting end devices.