A string containing the "Identity Association Identifier" (IAID) used by the DHCP client.
The property is a 32-bit decimal value or a special value among "mac", "perm-mac", "ifname" and "stable". When set to "mac" (or "perm-mac"), the last 4 bytes of the current (or permanent) MAC address are used as IAID. When set to "ifname", the IAID is computed by hashing the interface name. The special value "stable" can be used to generate an IAID based on the stable-id (see connection.stable-id), a per-host key and the interface name. When the property is unset, the value from global configuration is used; if no global default is set then the IAID is assumed to be "ifname". Note that at the moment this property is ignored for IPv6 by dhclient, which always derives the IAID from the MAC address.