Address Resolution Protocol (ARP) test—The unit’s ARP cache is evaluated for the ten
most recently acquired entries. One at a time, the Security Appliance sends ARP requests
to these machines, attempting to stimulate network traffic. After each request, the unit
counts all received traffic for up to 5 seconds. If traffic is received, the interface is
considered operational. If no traffic is received, an ARP request is sent to the next
machine. If, at the end of the list, no traffic has been received, the ping test begins.