SD-WAN-ENGINEER practice question 14 of 15

An administrator has configured a Path Policy for "ERP_Traffic". The policy allows two public internet links, "ISP-A" and "ISP-B", both marked as…

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An administrator has configured a Path Policy for "ERP_Traffic". The policy allows two public internet links, "ISP-A" and "ISP-B", both marked as "Active". The Path Quality Profile (SLA) requires a latency of less than 150ms. Currently, both ISP-A and ISP-B have a latency of 40ms, well within the SLA. How does the Prisma SD-WAN ION determine which link to use for a new flow of "ERP_Traffic" when both active paths meet the SLA requirements?
Answer options
A: It selects the path with the lowest numerical latency (e.g., if ISP-A drops to 39ms).
B: It selects the path with the highest available bandwidth capacity. Correct answer
C: It duplicates the packets across both paths (Packet Duplication) to ensure delivery.
D: It selects the path that appears first in the interface configuration list.
Correct Answer:
B. It selects the path with the highest available bandwidth capacity.
Explanation

When a Prisma SD-WAN Path Policy has multiple links configured as "Active" and all of them meet the specified Path Quality Profile (SLA), the ION device load-balances new sessions across these healthy paths. While the default load-balancing method is based on a 5-tuple hash for even distribution, Prisma SD-WAN also supports weighted load balancing. This allows for distributing traffic proportionally based on circuit capacity, meaning a link with higher available bandwidth can be allocated more sessions. Among the given options, selecting the path with the highest available bandwidth is a valid load-balancing strategy, whereas the other options describe entirely different policy types or features.

Why Incorrect

A. This describes the behavior of a "Best Path" policy with latency as the metric, not an "Active" policy where load balancing is the goal.
C. Packet Duplication is a specific feature for critical, loss-sensitive traffic that must be explicitly configured and is not the default behavior for an Active/Active policy.
D. This describes the logic for a "Primary/Backup" policy, where the first path is used exclusively until it fails, which contradicts the "Active" configuration.

References

1. Palo Alto Networks Prisma SD-WAN 6.3 Administrator's Guide, Chapter: Policies, Section: Path Policies > Configure Path Policy Rules.

Path Disposition > Active: "When multiple paths are configured as Active, the ION device load balances new sessions for the application across all the available healthy paths." This confirms that load balancing is the correct behavior for the scenario.

Load Balancing: "Prisma SD-WAN uses a 5-tuple hash... to determine the path for a new session... You can also configure weighted load balancing to distribute traffic based on the capacity of the circuits." This supports option B as a valid, configurable load-balancing method based on bandwidth capacity.

2. Palo Alto Networks Prisma SD-WAN 6.3 Administrator's Guide, Chapter: Policies, Section: Path Policies > Configure Path Policy Rules.

Path Disposition > Best Path: "The ION device selects the best path for the application based on the path metric you select (MOS, Jitter, Latency, or Packet Loss)." This directly refutes option A, as it describes a different policy type.

Path Disposition > Primary/Backup: "The ION device selects the primary path for the application. If the primary path becomes unhealthy, the ION device switches to the backup path." This directly refutes option D.

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