A network engineer implements an L3Out inside the Cisco ACI fabric. The engineer plans to connect a Cisco ACI leaf switch to a switch outside of the Cisco ACI fabric to exchange routes via a routing…

BGP is a path-vector routing protocol primarily used for inter-domain routing between autonomous systems, not typically for internal hierarchical routing within a single organization or for simple external connections to provide Internet access from an internal fabric that prefers a hierarchical design for this specific L3Out use case.

EIGRP, while a powerful hybrid routing protocol, uses an Autonomous System number but doesn't inherently enforce a hierarchical area-based design in the same manner as OSPF, making it less suitable when a specific hierarchical network design is explicitly requested.

EIGRP, similar to choice B, uses an Autonomous System number but lacks the explicit hierarchical area-based design requested by the problem statement, which points more directly to OSPF's area concept for routing segmentation.

OSPF is a link-state routing protocol known for its hierarchical design capabilities through the use of areas, with Area 0 (the backbone area) being central to inter-area routing. Configuring an OSPF Protocol policy with Area 0 in an L3Out allows the ACI fabric to establish routing adjacencies with external routers, facilitating Internet access.