Router R1 uses MAC address 1111.1111.1111 for its Fa0/0 interface. An engineer sees the
following configuration in the output of a show running-config command. Then, the engineer
issues a show ipv6 interface brief command. What global unicast IPv6 address does this
command display for interface tunnel 1?
interface loopback 1
ip address 192.168.1.1 255.255.255.255
interface tunnel 1
tunnel source loopback 1
tunnel destination 192.168.1.2
tunnel mode ipv6ip isatap
ipv6 address 2000::/64 eui-64

A.
2000::1311:11FF:FE11:1111

B.
2000::C0A5:101

C.
2000:C0A5:101::

D.
2000::5EFE:C0A5:101

Explanation:
The combination of the configured eui-64 parameter on the ipv6 address command,
and the tunnel mode of isatap, tells the router to use modified EUI-64 rules.
These rules start with the configured 64 bit prefix (2000::/64 in this case), adding
0000:5EFE as the fifth and sixth quartets. The last two quartets are taken from the
tunnel source command’s referenced IPv4 address. In this case, 192.168.1.1 converts
to C0A8:0101, making the last answer correct.