ARP table MIB data source

The MIB-II ARP table provides a mapping of IP addresses to MAC addresses for any neighboring system that has recently communicated with the system with this MIB. However, because the ARP MIB is populated only when the system resolves the addresses of neighboring systems that are connected with a broadcast network protocol such as Ethernet, the ARP MIB is not appropriate for use in WANs, which typically use a non-broadcast protocol.