Which option is NOT a method of VPN Tunnel sharing?

VPN tunnel sharing methods allow multiple connections to utilize the same VPN tunnel, optimizing resource use and managing connections efficiently. Each method has its particular application scenarios.

Gateway-based sharing focuses on sharing a single VPN tunnel across multiple gateways. This allows the security architecture to consolidate traffic and ensure a single point of management and encryption for many users or devices.

Subnet-based sharing involves allowing VPN access for all devices within a specified subnet. This approach is beneficial in larger networks where entire segments can be connected through a common tunnel, simplifying management while maintaining security.

Host-based sharing entails a unique instance of the VPN tunnel for each device or user. This allows for individualized sessions while still maintaining strong security protocols, ensuring that traffic remains isolated between different users.

Considering these definitions, IP range-based sharing isn't recognized as a standard method of VPN tunnel sharing in conventional practices. It doesn’t fit the established methods where typically defined network structures—such as gateways and subnets—are used to facilitate categorized access or define tunnel configurations. Thus, it stands out as the exception.