The ARP refresh feature allows the router to periodically verify ARP table entries. Whenever the router updates an ARP entry, or creates a new entry, a timeout value is assigned to the entry. When the timeout for an entry expires, the router will send a unicast ARP request to the currently-known physical address. If an ARP response comes back, the entry will be assigned a new timeout. If, however, the host has gone away or been assigned a new physical address, the host will not respond to the unicast ARP, and the entry will be removed from the ARP table. The new physical address will be discovered through the normal ARP mechanism when the next communication is attempted to the host.