Exam SD-WAN-Engineer Topic 3 Question 50 Discussion

In the Prisma SD-WAN architecture, reachability between sites is managed by the Control Plane, which automatically advertises prefixes across the secure fabric based on their scope. If a branch site has successful Direct Internet Access (DIA) but is invisible to the Data Center (DC), it indicates that while the local ION is online, its internal network information has not been propagated to the rest of the SD-WAN fabric.
The most common cause for this behavior is that the LAN interfaces or static routes at the branch are configured with a Local scope rather than a Global scope. When a prefix is set to "Local," the ION device treats that network as reachable only within that specific site; it will not advertise that prefix to the Controller for distribution to other ION devices, such as those at the Data Center. By ensuring the LAN branch prefixes are set to "global" (Option B), the administrator instructs the ION device to share these routes with the global fabric.
Once the prefix is marked as global, the Prisma SD-WAN Controller identifies it as a reachable destination and updates the routing tables of all peer ION devices in the same domain, including the DC gateways. This allows the Data Center to build a valid path to the branch resources over the secure VPN tunnels. Options like creating static routes (Option A) or changing site modes (Option C) do not address the fundamental requirement of prefix advertisement within the software-defined fabric, which relies on correctly defined metadata like route scope.