# Proxy ARP and NAT

Automatic proxy ARP requires an explicit route to the host or network to be configured in the Routing pane of the Engine Editor.

Proxy ARP (Address Resolution Protocol) is a specification that allows a device to respond to ARP requests on behalf of some other device on the network. When network address translation is used on a engine, the engine is typically configured to use proxy ARP so that it can accept packets for the translated addresses. The engine uses proxy ARP instead of requiring the administrator to assign all the translation addresses to the engine’s network interface.

In the Engine, proxy ARP is handled automatically. Proxy ARP is enabled by default in the NAT cell in NAT rules for each translation type, although you can deselect it, if necessary.