Which underlay characteristics most influence path selection in SD-WAN?

• A. Color of cables and aesthetics.
• B. Latency, bandwidth, reliability, and cost.
• C. Device footprint and power consumption only.
• D. Application layer protocols only.

Answer: (B)

Path selection in SD-WAN hinges on underlay metrics that reveal how a network path will actually perform for traffic. Latency measures how long packets take to travel, which directly affects how responsive real-time apps feel. Bandwidth shows the available data rate on a path, ensuring there’s enough room for the application’s traffic without causing congestion. Reliability captures how consistently a path delivers traffic and how often it might fail, which is critical for keeping business-critical services up. Cost reflects the monetary or tariff impact of using that path, letting the system favor cheaper options when performance is similar. By weighing these factors, the SD-WAN can steer each application onto the best path for its needs, balancing performance and expense.

Other options don’t fit because they focus on attributes that don’t determine how a path performs, such as cable aesthetics, or on hardware footprint, or on application-layer details that don’t govern the underlying transport path.