Cisco's internetworking model consists of which layers?

• A. Core, Spine, Leaf
• B. Core, distribution, access
• C. Physical, Data Link, Network
• D. Application, Presentation, Session

Answer: (B)

Cisco’s internetworking model uses a three-layer hierarchy: access, distribution, and core. The access layer is where end devices connect to the network—think switches at the edge that handle user devices and apply basic security and QoS. The distribution layer sits between the access and core, aggregating traffic from multiple access switches, performing inter-VLAN routing, enforcing policies, and providing redundancy. The core layer is the fast, high-capacity backbone that moves large amounts of data between distribution blocks with minimal processing so it doesn’t become a bottleneck.

This setup is described by the option that lists core, distribution, and access as the layers, which aligns with Cisco’s three-layer model. Other choices reflect different architectures or models—for example, spine-leaf describes data-center fabrics, and the Physical, Data Link, Network or Application, Presentation, Session groupings refer to OSI model layers, not Cisco’s internetworking hierarchy.