Exam JN0-664 topic 1 question 7 discussion

To transport IPv6 traffic over an IPv4-based MPLS network using BGP, you need to configure two address families: family inet6 labeled-unicast and family inet6 unicast. The former is used to exchange IPv6 routes with MPLS labels between PE routers, and the latter is used to exchange IPv6 routes without labels between PE and CE routers. The mpis ipv6-tunneling command enables the PE routers to encapsulate the IPv6 packets with an MPLS label stack and an IPv4 header before sending them over the MPLS network.

A&D is correct. The question is about the provider network, need to enable both v6 labeled unicast and v6 unicast between PEs.

A& C

AC, reason exhibit is given with PE-CE, we cant ignore its PE-PE

Note that the question asks about BGP configuration which is PE to PE. There is no mention of BGP running between PE and CE here, so any answer involving PE to CE is wrong.