Final answer:
In Stateful DHCPv6, a client uses EUI-64 format or a randomly generated identifier to create the rest of its IPv6 address after receiving the network prefix.
Step-by-step explanation:
Stateful DHCPv6 and IPv6 Address Generation
In Stateful DHCPv6, when a client receives the network prefix, it uses the Extended Unique Identifier (EUI-64) format or a randomly generated interface identifier to generate the remaining portion of its IPv6 address. This method involves modifying the MAC address of the network interface card (NIC) to fit the EUI-64 standard, which includes inserting the hexadecimal number FFFE in the middle of the MAC address and inverting the seventh bit. In some cases, systems avoid using EUI-64 due to privacy concerns, opting instead for a randomly generated interface identifier as per RFC 7217.