|  | 11.7 | ARP Tables
| 11.7.5 | Proxy ARP
A device on one network cannot send an ARP request to a device on another network. Can you think of a reason why this is so? What happens in the case of subnetworks? Can a device on one subnetwork find the MAC address of a device on another subnetwork? The answer is yes, provided the source directs its question to the router. Working through a third party is called proxy ARP, and it allows the router to act as a default gateway.