What is dynamic path selection in SD-WAN and what metrics influence path choice?

• A. It selects the path with the lowest cost.
• B. It guarantees use of the primary WAN link at all times.
• C. It chooses the best WAN path among available transports based on latency, jitter, packet loss, bandwidth, SLA requirements, and policy.
• D. It ignores network conditions and relies on static routing.

Answer: (C)

Dynamic path selection in SD-WAN means choosing the best available WAN path for each traffic flow based on real-time measurements and policy rules. An SD-WAN edge monitors multiple transports (like MPLS, broadband, and cellular) and uses a decision engine to steer traffic to the path that will meet performance goals. The decision relies on several metrics: latency (how long packets take to reach the destination, important for time-sensitive applications), jitter (variation in delay, which can disrupt streaming or voice), packet loss (which reduces effective throughput and can trigger retransmissions), and available bandwidth on each link (to ensure the path can handle the application's demand). Policy and SLA requirements layer on top, guiding decisions for business-critical applications and ensuring service commitments are met. Because conditions change, the edge can continuously reevaluate paths and shift traffic to maintain performance or perform failover if a path degrades.

Other options don’t fit because just picking the lowest cost path ignores performance and policy implications, so it wouldn’t guarantee acceptable application experience. Always using the primary link contradicts the idea of using other paths when conditions worsen. Relying on static routing ignores real-time network conditions entirely, which is the opposite of dynamic, telemetry-driven path selection.