Which functionality is required within an IP router that is situated at the boundary of an IPv4 network and an IPv6 network to allow communication between IPv6-only and IPv4-only nodes?
Select the best response.

A.
Autoconfiguration

B.
Automatic 6to4 Tunnel

C.
Automatic 6to4 Relay

D.
Network Address Translator-Protocol Translator (NAT-PT)

E.
Intrasite Automatic Tunnel Address Protocol (ISATAP)