In Cisco's three-layer model, which layer directly interfaces with end-user devices?

• A. Aggregation Layer
• B. Core Layer
• C. Access Layer
• D. Distribution Layer

Answer: (C)

The layer that directly interfaces with end-user devices is the one at the edge of the network. It provides the actual connection points for PCs, printers, IP phones, and other user equipment, handling things like port configuration, authentication (such as 802.1X), VLAN assignment, and basic security. In Cisco’s three-layer model, this is the Access Layer—the point where devices physically connect and gain network access.

The other layers serve different roles and don’t directly connect to end-user devices. The Core is the fast backbone that interconnects distribution points and moves traffic quickly across the network. The Distribution (often called Aggregation in some contexts) aggregates connections from the access layer, enforces policies, and handles inter-VLAN routing and redundancy.