Which statement describes the difference between a manually configured IPv6 in IPv4
tunnel versus an automatic 6to4 tunnel?

A.
A manually configured IPv6 in IPv4 tunnel allows multiple IPv4 destinations.

B.
An automatic 6to4 tunnel allows multiple IPv4 destinations.

C.
A manually configured IPv6 in IPv4 tunnel does not require dual-stack (IPv4 and IPv6)
routers at the tunnel endpoints.

D.
An automatic 6to4 tunnel does not require dual-stack (IPv4 and IPv6) routers at the
tunnel endpoints.

Explanation:
An automatic 6to4 tunnel allows isolated IPv6 domains to be connected over an IPv4
network to remote IPv6 networks. The key differencebetween automatic 6to4 tunnels and
manually configured tunnels is that the tunnel is not point-to-point; it is point-to-multipoint ->
it allows multiple IPv4 destinations -> “An automatic 6to4 tunnel allows multiple IPv4
destinations. is correct.
“A manually configured IPv6 in IPv4 tunnel allows multiple IPv4 destinations” is not
correct because manually 6to4 is point-to-point -> only allows one IPv4 destination.
A is not correct because manually 6to4 is point-to-point -> only allows one IPv4 destination.
Configuring 6to4 (manually and automatic) requires dual-stack routers (which supports both
IPv4 & IPv6) at the tunnel endpoints because they are border routers between IPv4 & IPv6
networks.