Router R2 has an interface named Gigabit Ethernet 0/2, whose MAC address has been set to 5555.4444.3333. This interface has been configured with the ipv6 address 7000:1:1:1::/64 eui-64 subcommand. What unicast address will this interface use?

(A) 7000:1:1:1:55FF:FE55:4444:3333
(B) 7000:1:1:1:5755:44FF:FE44:3333
(C) 7000:1:1:1:5555:4444:33FF:FE33
(D) 7000:1:1:1:200:FF:FE00:0

7000:1:1:1:5755:44FF:FE44:3333 is the correct answer. With the eui-64 parameter, the router will calculate the interface ID portion of the IPv6 address based on its MAC address.

Beginning with 5555.4444.3333, the router injects FF FE in the middle (5555.44FF.FE44.3333). Then the router inverts the seventh bit in the first byte. Mentally, this converts hex 55 to binary 0101 0101, changing the seventh bit so the string is 0101 0111 and converting back to hex 52. The final interface ID value is 5755:44FF:FE44:3333