JN0-352 Practice Questions

Nonstop active routing is specifically engineered to be completely transparent to the rest of the network: rather than relying on neighboring routers to preserve state during a Routing Engine switchover the way graceful restart does, NSR keeps a fully synchronized instance of the routing protocol process (rpd) running continuously on the backup Routing Engine, mirroring protocol adjacencies, the RIB, and session state in real time. Because neighbors never observe a session reset or restart signal during an NSR-driven switchover, there is no dependency on those neighbors supporting or enabling graceful restart extensions at all — this is the core architectural advantage that distinguishes NSR from GR and is precisely why the first and third answer choices are incorrect distractors. What NSR does require locally is Graceful Routing Engine Switchover (GRES) enabled first, since NSR is built as an extension on top of GRES and depends on it to synchronize kernel and interface state between the two Routing Engines before protocol-level synchronization can occur. Additionally, Juniper's official guidance mandates that both Routing Engines run the identical Junos OS software version; mismatched versions between the primary and backup Routing Engine can introduce incompatible internal data structures or feature behavior during state replication, jeopardizing the integrity of a switchover and is explicitly called out as a hard operational requirement rather than a mere best practice. Reference topics: Junos Enterprise Routing – High Availability, Nonstop Active Routing Requirements and GRES Dependency.

IS-IS (Intermediate System to Intermediate System) was designed by ISO as a link-state Interior Gateway Protocol for routing within a single autonomous system, functioning on a hierarchical two-level model conceptually similar to OSPF's areas, which makes the first statement unambiguously correct. Within that hierarchy, Level 1 routers maintain detailed topology information only for their own local area and use a default route toward the nearest Level 2 or Level 1/Level 2 router to reach destinations outside the area; they explicitly do not carry inter-area topology information and therefore cannot route traffic between areas on their own. Routers that participate in both levels simultaneously — Level 1/Level 2 (L1/L2) routers — sit at the area boundary, maintaining a Level 1 database for their local area and a Level 2 database for the backbone, and it is specifically these dual-level routers that stitch inter-area traffic together, forwarding packets from the local area into the Level 2 backbone and vice versa, which confirms the second correct statement. Regarding route preference, Junos assigns distinct default preference (administrative distance) values of 15 for IS-IS Level 1 routes and 18 for IS-IS Level 2 routes — neither of which is 20 — so the preference-value statement is factually incorrect and included as a distractor testing precise knowledge of Junos default protocol preferences. Reference topics: Junos Enterprise Routing – IS-IS, Level 1, Level 2, and L1/L2 Router Roles; Default Route Preference Values.

This detailed adjacency output shows R3 maintaining four separate, fully Up adjacencies, evenly split between the two IS-IS levels. R1 and R2 are both formed at Level 1, confirming that R3 is directly adjacent to exactly two Level 1 neighbors within its local area, which validates that statement. R4 and R5 are both formed at Level 2, and Level 2 adjacencies are, by definition, part of the IS-IS backbone that interconnects areas; a router maintaining any Level 2 adjacency is by that fact participating in and connected to the Level 2 backbone, confirming R3's backbone connectivity as well. Every one of the four listed adjacencies explicitly shows 'Speaks: IP, IPv6' in its detail output, which is Junos's way of indicating that both the IPv4 and IPv6 address families have been successfully negotiated and are active over that circuit; this directly contradicts, rather than supports, the claim that IPv6 is disabled on these neighbors — if IPv6 were disabled, the Speaks field would list only IP. Regarding authentication, the output contains no field, flag, or indication whatsoever referencing authentication configuration or state for the R5 adjacency (or any adjacency); Junos would typically surface authentication-related information separately if it were configured and relevant, and its complete absence here means no basis exists in the exhibit to conclude authentication is required for that specific adjacency. Reference topics: Junos Enterprise Routing – IS-IS, Level 1 and Level 2 Adjacencies and Address Family Negotiation.