The following configuration exists on a router on one end of an IPv6 tunnel. Although the
configuration added so far is correct, the configuration is incomplete.
Which type of tunnel is most likely to be intended by the network engineer?
interface loopback 1
ip address 192.168.1.1 255.255.255.255
interface tunnel 2
ipv6 address 2002:C0A8:101::1/64
tunnel source loopback 1

A.
Automatic 6to4

B.
Manually configured tunnel

C.
ISATAP

D.
GRE

Explanation:
An automatic 6to4 tunnel does not use a tunnel destination command on the tunnel
interface; ISATAP tunnels also do not use this command. However, automatic 6to4 tunnels
use IPv6 addresses that begin 2002::/16 and have the tunnel’s source IPv4 address
imbedded as the second and third octets of the IPv6 address, whereas ISATAP tunnels do
not. Because C0A5:101 hex equals 192.168.1.1 in dotted decimal, this configuration
represents the almost completed configuration for an automatic 6to4 tunnel.