Which of the following methods does the FortiGate unit use to determine the availability of a web cache using Web Cache Communication Protocol (WCCP)?

While WCCP involves 'Here I am' messages from the cache, FortiGate's determination of availability often extends beyond passive reception to include active health checks for more robust monitoring.

The specific mechanism for WCCP health in FortiGate is typically referred to as a health check monitor, which is a more defined process than merely 'polling all globally-defined web cache servers'.

FortiGate units utilize health check monitors to actively verify the operational status and availability of configured WCCP web cache servers. This proactive monitoring ensures that traffic is only redirected to functioning caches, maintaining service reliability and preventing service disruptions.

'I see you' messages are not a standard or primary method FortiGate uses for WCCP web cache availability determination; the 'Here I am' message from the cache is part of WCCP, but active health checks are also crucial.