Which layer/interface in Cisco DNA Center exposes REST controls?

Cisco DNA Center uses northbound APIs to expose REST controls, allowing external systems and applications to programmatically interact with and manage the network. These APIs provide a standardized way for other software to request information, configure devices, and automate tasks within the DNA Center environment. The session layer is part of the OSI model and deals with communication sessions, not the exposure of REST controls. EEM applets or scripts are used for on-device automation and event handling, not for external API exposure. YAML output is a data serialization format for API responses, not the interface that exposes the controls themselves.