In MEF SD-WAN service attributes, underlay type refers to what?

• A. The authentication credentials
• B. The cloud provider name
• C. The physical or transport network used to carry traffic
• D. The application layer protocols

Answer: (C)

Underlay type refers to the physical or transport network that carries traffic between SD-WAN edge devices. In MEF SD-WAN, the overlay tunnels ride on top of this underlying connectivity, so the underlay can be private MPLS, broadband Internet, cellular links, or other provider networks. Knowing the underlay type helps determine how traffic is transported, how performance characteristics (latency, jitter, bandwidth) affect the overlay, and how paths are chosen and managed. It’s not about authentication credentials, cloud provider name, or application-layer protocols.