Definition: SLAAC

(StateLess Address Auto Configuration) The preferred method of assigning IP addresses in an IPv6 network. SLAAC devices send the router a request for the network prefix, and the device uses the prefix and its own MAC address to create an IP address. After the IP is computed, it checks to see if a duplicate IP was previously created.

DHCP Is Used If SLAAC Is Not Supported
If the router does not implement SLAAC and no network prefix is received, the device sends a request to the DHCPv6 server, which responds with an IP address similar to the DHCP in IPv4. See IPv6.