Which layer is primarily responsible for high-speed backbone routing and interconnections between distribution switches?

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

Answer: (A)

In a hierarchical network design, the Core Layer acts as the fast, high-capacity backbone that interconnects distribution devices. Its primary role is to move traffic quickly between distribution switches and provide a reliable, low-latency path across the network. Because the core is meant to be fast and simple, it typically avoids policy enforcement or complex routing decisions, focusing instead on fast switching and redundancy to keep data flowing smoothly.

The distribution layer sits between the access layer and the core, handling inter-VLAN routing, policy enforcement, and aggregation of traffic from multiple access devices. The access layer is where end devices connect, providing user access and initial edge services. Some architectures reference an Aggregation Layer in data-center designs, which can sit between access and core or map to distribution in other models, but the description of a high-speed backbone interconnecting distribution switches points to the Core Layer.