In a Layer 3 device, where is the exchange of routing information primarily carried out?

The correct answer is that the exchange of routing information in a Layer 3 device primarily occurs in the Control Plane. The Control Plane is responsible for all the routing decisions and the handling of routing protocols, which includes the exchange and maintenance of routing information used to build and update the routing table.

While Cisco Express Forwarding (CEF) is an efficient method for packet forwarding that takes place in the Data Plane, it relies on the routing information that the Control Plane provides. CEF allows packets to be forwarded quickly once the routing decisions have already been made, but it does not handle the initial routing information exchange itself.

Routing Information Protocol (RIP) is a specific routing protocol that operates in the Control Plane directly but is just one of the many methods for exchanging routing information; it does not encompass the entire process on its own. Centralized Ethernet Forwarding is not a standard term related to the functioning of Layer 3 devices and doesn't pertain to routing information exchange. Thus, the most accurate context for routing information exchange fundamentally lies within the Control Plane.