Which two components do southbound APIs use to communicate with downstream devices? (Choose two.)

Services running over the network is a generic description of network traffic and does not refer to specific southbound API protocols.

OpenFlow is a widely recognized, open standard southbound protocol used by an SDN controller to communicate with and program the data plane of network devices, enabling centralized control.

External application APIs typically refer to northbound APIs that allow applications to interact with the SDN controller, not directly with network devices.

Applications running over the network describes network traffic generated by applications, not the specific API protocols used by controllers to manage devices.

OpFlex is a Cisco-developed, declarative southbound protocol used in Cisco Application Centric Infrastructure (ACI) to facilitate communication between the APIC controller and network devices, translating policy into device-specific configurations.