Which two content caching settings can optimize internet bandwidth for Apple devices over three network subnets?

Choosing to cache content for devices using custom local networks alongside caching content for devices sharing the same public IP address effectively optimizes internet bandwidth for Apple devices across multiple network subnets.

By enabling caching for devices connected to specific custom local networks, the caching service can store frequently accessed content locally. This reduces the need for devices to fetch data from the internet repeatedly, which is especially beneficial when multiple devices are accessing the same resources or updates. By additionally caching for devices that share the same public IP address, this setting accommodates different subnets that might be using a network address translation (NAT) setup. This approach ensures that devices on different subnets but sharing public-facing IP addresses can benefit from the same cached content, thereby further optimizing bandwidth use.

The other options present settings that do not effectively address the scenario of optimizing internet bandwidth over three different subnets. They focus on caching criteria not suited for multi-subnet environments, like limiting caching to VPN connections, mobile data users, or even offline mode, which are less relevant to maximizing efficiency across public IP addresses or local networks in a diverse subnet configuration.