Exam JN0-336 Topic 1 Question 49 Discussion

The correct answers are B and C. In Junos route-based IPsec VPNs, the default proxy ID is broad: local 0.0.0.0
/0, remote 0.0.0.0/0, and service any. This default behavior allows routed traffic entering the secure tunnel interface to determine what is protected by the VPN rather than requiring a narrow policy-based encryption domain. Juniper's IPsec VPN configuration guidance also states that proxy IDs are used in Phase 2 negotiations, and that a proxy ID mismatch is one of the common causes of Phase 2 failure. For interoperability with some third-party VPN peers, Juniper notes that proxy IDs may need to be manually configured to match the peer.
Option A is wrong because proxy IDs can override default route-based behavior when manually configured, especially when a peer requires specific local and remote protected subnets. Option D is wrong because proxy IDs are not created during IKE Phase 1. Phase 1 builds the secure IKE channel; proxy IDs belong to Phase 2
/IPsec SA negotiation, where the peers agree on traffic selectors for encrypted traffic. Reference topics: IPsec VPN, route-based VPNs, proxy IDs, Phase 2 negotiation, traffic selectors, third-party VPN interoperability.