Which two tunneling techniques in IPv6 do not require an IPv4 tunnel destination in the configuration?

Which two tunneling techniques in IPv6 do not require an IPv4 tunnel destination in the
configuration? (Choose two.)

A.
6to4

B.
6over4

C.
ISATAP

D.
GRE

Explanation:
Example: Configuring 6to4 Tunnels
The following example configures a 6to4 tunnel on a border router in an isolated IPv6 network.
The IPv4 address is 192.168.99.1, which translates to the IPv6 prefix of 2002:c0a8:6301::/48. The
IPv6 prefix is subnetted into 2002:c0a8:6301::/64 for the tunnel interface: 2002:c0a8:6301:1::/64
for the first IPv6 network, and 2002:c0a8:6301:2::/64 for the second IPv6 network. The static route
ensures that any other traffic for the IPv6 prefix 2002::/16 is directed to tunnel interface 0 for
automatic tunneling.
interface Ethernet0
description IPv4 uplink
ip address 192.168.99.1 255.255.255.0
!
interface Ethernet1

description IPv6 local network 1
ipv6 address 2002:c0a8:6301:1::1/64
!
interface Ethernet2
description IPv6 local network 2
ipv6 address 2002:c0a8:6301:2::1/64
!
interface Tunnel0
description IPv6 uplink
no ip address
ipv6 address 2002:c0a8:6301::1/64
tunnel source Ethernet 0
tunnel mode ipv6ip 6to4
!
ipv6 route 2002::/16 tunnel 0
Example: Configuring ISATAP Tunnels
The following example shows the tunnel source defined on Ethernet 0 and the tunnel mode
command used to configure the ISATAP tunnel. Router advertisements are enabled to allow client
autoconfiguration.
ipv6 unicast-routing
interface tunnel 1
tunnel source ethernet 0
tunnel mode ipv6ip isatap
ipv6 address 2001:DB8::/64 eui-64
no ipv6 nd ra suppress
exit