Output Interface: Serial1/0
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to FE80::2, timeout is 2 seconds:
Packet sent with a source address of FE80::5
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/8/12 ms
Why must you specify an output interface when pinging FE80::2?
Highlight for answer: FE80::2 is an IPv6 link-local address. IPv6 link-local address do not need to be unique on a router, but must be unique on an interface. Because the same IPv6 link-local address can be present on multiple interfaces on a device, IOS needs to know the output interface.