When planning a software upgrade for a large fleet of ION devices, what is the recommended best practice regarding the "Software Version" assigned in the Site Summary?

The recommended best practice for upgrading a large fleet of ION devices is to perform a phased or staged rollout. Using Site Tags allows an administrator to group sites logically (e.g., by region, function, or rollout phase). By assigning the new software version to a small "Pilot" tag first, the new version can be validated in a controlled production environment. If the pilot upgrade is successful, the administrator can then proceed to assign the new version to subsequent groups incrementally, which significantly minimizes the risk of a network-wide service disruption.

A. Manually log into each device and upload the new image file via USB. This method is not scalable for a large fleet of devices and is operationally inefficient and prone to human error.
B. Assign the new software version to the "Global" site configuration to upgrade all 1000+ sites simultaneously. This approach is extremely high-risk. A single issue with the new software could cause a catastrophic, network-wide outage.
D. The ION devices upgrade themselves automatically whenever a new version is released by Palo Alto Networks. ION device upgrades are not automatic upon release. An administrator must explicitly select and assign a target software version to sites via the controller to initiate the upgrade process.

1. Palo Alto Networks Prisma SD-WAN Administrator’s Guide 6.3: In the section "Upgrade ION Device Software," the guide explicitly states, "For a large-scale deployment, it is recommended to perform a phased rollout of the software upgrade. You can use site tags to group sites into various phases of the rollout." This directly supports the methodology described in option C. (Reference: Prisma SD-WAN Administrator’s Guide 6.3, Chapter: Device and Software Management, Section: Upgrade ION Device Software).

2. Palo Alto Networks Prisma SD-WAN Administrator’s Guide 6.3: The same guide details the process of assigning a software version to a site or group of sites. The process requires an administrator to navigate to the site list, select the sites, and choose "Software" > "Assign." This confirms that the upgrade is an administrator-initiated action, refuting the claim of automatic upgrades in option D. (Reference: Prisma SD-WAN Administrator’s Guide 6.3, Chapter: Device and Software Management, Section: Upgrade ION Device Software, Step 3).