Pearson 350-401 New Attempt

The correct answer is A. interface between the controller and the network devices.

In Cisco controller-based architectures such as Cisco DNA Center / Cisco Catalyst Center, APIs are generally described in two directions:

Northbound APIs → used by external applications, users, or orchestration systems to communicate with the controller

Southbound APIs → used by the controller to communicate with the network devices

A southbound API provides the communication path between the controller and the infrastructure devices such as switches, routers, and wireless devices. This is how the controller pushes configuration, collects operational data, and manages the network.

B. interface between the controller and the consumer This describes a northbound API, not a southbound API.

C. NETCONF API interface for orchestrator communication Orchestrator communication is generally associated with northbound integration, not the fundamental definition of Cisco DNA southbound APIs.

D. RESTful API interface for orchestrator communication This also describes northbound API behavior, where external systems communicate with the controller.

Remember this controller model clearly:

Northbound API = controller ↔ applications / orchestration / users

Southbound API = controller ↔ network devices

Southbound = toward the infrastructure

The correct answer is B. To route video traffic through a dedicated link.

Policy-Based Routing (PBR) allows the router to make forwarding decisions based on policies such as source, destination, application, or other match criteria, instead of relying only on the routing table. Cisco documentation explains that PBR gives more control over routing by reducing reliance on routes learned from routing protocols, and that it can route traffic according to a defined policy.

This means an engineer can identify video traffic and force it to use a specific dedicated path or link, even if that path is not the normal best path chosen by the routing table. Cisco also notes that set ip next-hop makes the system use policy routing first and then the routing table, which confirms that PBR can override normal routing behavior to send selected traffic to a chosen next hop.

Video traffic is often sensitive to delay, jitter, and packet loss. With PBR, the engineer can match that traffic and send it over a dedicated WAN link or preferred path that better supports real-time applications. This is a classic use case for PBR.

A. To route video traffic using the shortest path to the destination This is normally the job of the routing table and routing protocols, not PBR. PBR is used when the engineer wants to override normal path selection.

C. To use multicast for video traffic transmission Multicast is a separate forwarding technology and is not the purpose of PBR.

D. To perform traffic shaping to avoid video traffic delay Traffic shaping is a QoS function, not a routing decision function. PBR selects paths; it does not shape traffic.

ENCOR exam point:

Use PBR when traffic must follow a policy-defined path rather than the path chosen by standard routing protocol metrics.