Final answer:
The EUI-64 format for stateless autoconfiguration in IPv6 addresses inserts FFFE in the MAC address and inverts the 7th bit to form a 64-bit interface ID.
Step-by-step explanation:
The EUI-64 address format is relevant to the generation of interface IDs for stateless autoconfiguration in IPv6 addresses. When using EUI-64 on Cisco devices, a 48-bit MAC address is modified to create a 64-bit interface ID. The process includes inserting the hex value FFFE in the middle of the MAC address, splitting the address into two 24-bit parts, and inverting the 7th bit (Universal/Local bit) of the original MAC address to indicate whether the address is locally administered or globally unique. This modified 64-bit value is then appended to the local network prefix to form the full IPv6 address.