Final answer:
Southbound APIs allow program control of the network while both northbound and southbound APIs do not use a Service Abstraction Layer.
Step-by-step explanation:
Northbound and southbound APIs are used in software-defined networking (SDN) to control and manage network devices. Northbound APIs allow external applications to communicate with the SDN controller, while southbound APIs enable the controller to communicate with network switches or routers.
Statement 1: Only southbound APIs allow program control of the network. This statement is true because southbound APIs are responsible for sending instructions to the network devices, allowing programmatic control over them.
Statement 3: Both northbound and southbound API interfaces use a Service Abstraction Layer. This statement is false because the Service Abstraction Layer is typically used in northbound API interfaces to provide a consistent interface for external applications, while southbound APIs deal directly with network hardware.