When a ProxySG appliance connects to your network, it completes the ARP (Address Resolution Protocol) table of physical addresses to interconnected devices. This article details for how long the information in the ProxySG appliance's ARP table is retained.
For more information on ARP, see: https://en.wikipedia.org/wiki/Address_Resolution_Protocol.
The proxy keeps information from ARP for five minutes before refreshing.
To flush the ARP information before the five minute refresh, please refer to article 000010435.