Router R1 has two LAN interfaces and three serial interfaces enabled for IPv6. All the
interfaces use link local addresses automatically generated by the router. Which of the
following could be the link local address of R1’s interface S0/0?

A.
FEA0::200:FF:FE11:0

B.
FE80::200:FF:FE11:1111

C.
FE80::0213:19FF:FE7B:0:1

D.
FEB0::211:11FF:FE11:1111

Explanation:
When created automatically, link local addresses begin FE80::/64, because after the prefix
of FE80::/10, the device builds the next 54 bits as binary 0s. Statically assigned link local
addresses simply need to confirm to the FE80::/10 prefix. As a result, only two answers are
candidates with a beginning quartet of FE80. Of these, only one has only hex 0s in the
second, third, and fourth quartets, making answer B the only valid answer.