This object determines whether the router drops or accepts an ARP request whose destination address is on a different network or subnetwork than its source address. The default, drop, protects against processing ARP requests that don't make sense for the local segment, while setting it to accept relaxes that check, which an admin might need in unusual multi-homed or proxy-ARP topologies. An admin running a nonstandard subnetting scheme where legitimate ARP requests cross what look like different subnets might set this object to accept(2) to stop those requests from being dropped.