Which interface enables communication between a program on the controller and a program on the networking devices?
Correct Answer: C
southbound interface. In controller-based networking, the southbound interface is the communication path between the controller and the network devices. Northbound APIs are used between applications and the controller. A switched virtual interface is a Layer 3 logical interface on a switch, not the controller-to-device programming interface. Cisco CCNA 200-301 v1.1 Automation and Programmability expects candidates to separate northbound and southbound roles cleanly. The question specifically asks about communication between a program on the controller and a program on networking devices, which is the southbound side of the architecture. The corrected answer is southbound interface. This is the direction used by mechanisms such as OpenFlow, NETCONF, RESTCONF, or other device-facing control and management protocols depending on the platform.