Which type of API is being used when a controller within a software-defined network architecture dynamically makes configuration changes on switches within the network?

'Westbound API' is not a standard term used in SDN architecture for controller-to-device communication.

Southbound APIs in SDN architecture are used by the controller to communicate with and control the underlying network devices, such as switches and routers. These APIs enable the controller to push configuration changes, retrieve status information, and manage the data plane dynamically.

Northbound APIs are used for communication between the SDN controller and applications or orchestration systems above it, allowing applications to request network services from the controller.

'Eastbound API' is not a standard term used in SDN architecture for controller-to-device communication; it sometimes refers to controller-to-controller communication within a distributed SDN setup.