This read-write value sets the maximum time, in seconds, that can pass without ARP activity for an entry before it's deleted from the ARP table, with a default of 0 meaning it falls back to the device-wide inactive timeout value. Admins configure this per-interface when they want different ARP aging behavior on that interface than the device-wide default, such as a longer timeout on a stable server-facing interface. For example, leaving this at 0 on most interfaces while explicitly overriding it with a longer value on a specific interface lets that interface retain ARP entries longer than the rest of the device.