Exam JN0-664 topic 1 question 93 discussion

Customer uses same AS number on two sites, that's why as-override is configured.

answer B,C BGP group type external

I would say B, C. Junos doesn't allow to configure a BGP neighbour as type external and also use the same ASN as the local router. Tested in lab: Error in neighbor 10.0.0.1 of group CE: external peer's AS (64512) must not be the same as the local AS (64512) error: configuration check-out failed

The question is really badly set. With the information provided, only absolutely correct option is B,C. It could be, that customer uses same AS on both sides of the L3VPN, but provided config snippet doesn't prove it right. You can also configure AS-override "just for sure", or if you just want to hide the originating AS even if it wans't overlapping. A,C could be right, but B,C is certainly right according what's provided.

BC BGP external

as-override for same AS number

A,C B can't be correct, as if so, then there's no need for "as-override".

A,C as as-override is used and bgp configuration toward CE

AS Override if you do not want neighbour's AS in the AS Path and have your own in there instead. So the neighbor might have the same AS as the other neither on the other side of the L3VPN. The other give away is, Group Type being EXTERNAL.