By default an Art-Net product will factory start using a Class A IP address scheme in the range 2.x.y.z. This allows Art-Net products to communicate directly and without the need for a DHCP server to be connected to the network.
However, the IP address can be changed by the user; for example, 10.x.y.z and 192.168.x.y are perfectly legitimate.
Art-Net 3 supports DHCP in addition to static addressing.