Exam JN0-664 topic 1 question 53 discussion

A is correct. IGP > EGP > ? (incomplete) which has values 0>1>2. I the path selection lower origin value is preferred.

• By default, PHP (Penultimate Hop Popping) removes the top MPLS label at the penultimate router (P-1), before the packet reaches PE-2. • This causes loss of EXP bits from the outer label, preventing PE-2 from classifying the traffic based on them. • Using explicit-null on PE-1 ensures the outer MPLS label is preserved, but with label value 0 (IPv4 explicit-null), so that EXP bits reach PE-2. • PE-2 can then read the EXP bits and classify the traffic correctly

A is correct.

Selected Answer: A Prefer the route with the lower origin code. Routes learned from an IGP have a lower origin code than those learned from an exterior gateway protocol (EGP), and both have lower origin codes than incomplete routes (routes whose origin is unknown). https://www.juniper.net/documentation/us/en/software/junos/vpn-l2/bgp/topics/concept/routing-protocols-address-representation.html

A is correct. IGP > EGP > ? (incomplete) which has values 0>1>2. I the path selection lower origin value is preferred.

C is correct. IGP > EGP > ? (incomplete).