The exhibit displays the SD-WAN Zones configuration page on a FortiGate. In FortiOS, virtual-wan-link is a default system-defined zone that cannot be deleted. User-defined zones, such as WAN1, can be deleted provided they contain no member interfaces and are not referenced elsewhere in the system configuration (e.g., in firewall policies or static routes). Based on the GUI exhibit, WAN1 lacks an expansion icon (+ or -), indicating it currently has no assigned members, making it eligible for deletion. Conversely, WAN2 displays a "+" icon, signifying it contains members. Finally, an interface can only belong to a single SD-WAN zone at any given time; therefore, a member cannot exist in two zones simultaneously.

A: The virtual-wan-link zone is a mandatory system-generated object in the FortiOS SD-WAN architecture and is protected from deletion to maintain system consistency.

B: The presence of the "+" expansion icon next to the WAN2 zone explicitly indicates that it contains one or more collapsed member interfaces.

D: FortiGate SD-WAN logic requires a 1:1 mapping between a physical or virtual interface and a zone; an interface cannot be a member of two zones at once.

Fortinet. FortiOS 7.2.0 Administration Guide: SD-WAN. Section: "SD-WAN zones," p. 2412.

Stanford University (Network Systems). Software Defined Wide Area Networking (SD-WAN) Principles. Courseware Module: "Interface and Zone Management in Enterprise Firewalls."