Juniper Updated JN0-352 Exam Questions and Answers by nella

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.

Configuring interface-type p2p under an OSPF interface tells Junos to treat that interface as a point-to-point network type regardless of the underlying physical medium, which removes the interface from the standard broadcast-network state machine entirely. On a true broadcast network, two routers must first complete a Designated Router and Backup Designated Router election, wait through the associated timers, and only then proceed through 2-Way, ExStart, Exchange, and Loading before reaching Full — a multi-step process. A point-to-point interface skips DR/BDR election altogether and proceeds directly from 2-Way into ExStart, so adjacencies form measurably faster, which is the first correct benefit. Because there is no DR on a point-to-point interface, Junos also does not generate a Type 2 Network LSA to describe the segment; the connected subnet is instead advertised as a simple stub-network entry inside the Router LSA itself, eliminating an entire LSA type from the area's link-state database and reducing its overall size, which is the second correct benefit. Point-to-point configuration is entirely incompatible with DR election, so a router configured this way cannot 'win' a DR election — there is no DR to win. Advertisement of the connected network happens on any operational OSPF interface irrespective of network type, so that option describes normal OSPF behavior rather than a benefit specific to the point-to-point setting. Reference topics: Junos Enterprise Routing – OSPF Network Types, Configuring OSPF Interface Type.

The virtual-router routing-instance type in Junos is a general-purpose instance type intended for creating isolated, independent routing and forwarding contexts within a single physical device for applications that have nothing to do with MPLS-based VPN services — common use cases include multi-tenant network segmentation, filter-based forwarding deployments, and simple traffic isolation between departments or customers on a shared switch or router, all of which are non-VPN-related applications by nature. Layer 2 and Layer 3 VPN services, by contrast, rely on a different, dedicated routing-instance type specifically named vrf, which integrates with MPLS/BGP-based VPN signaling, route distinguishers, route targets, and PE-CE routing exchange; virtual-router instances do not participate in that VPN signaling framework at all, which is why the statement associating virtual-router with VPN use is incorrect. Whenever an administrator creates any user-configured routing instance — regardless of its specific type — Junos automatically allocates and generates a brand-new, dedicated routing table for that instance, named according to the pattern instance-name.inet.0 (or the appropriate address-family suffix), which is entirely separate from and independent of the default master inet.0 table used by the global/default routing context. Because each new routing instance receives its own distinct table rather than sharing or defaulting into the master inet.0 table, the statement claiming instances automatically fall back to using inet.0 unless configured otherwise is factually incorrect; instances are isolated by design from the outset. Reference topics: Junos Enterprise Routing – Protocol Independent Routing, Routing Instance Types and Table Allocation.

A GRE-encapsulated packet consists of the original passenger packet wrapped inside a GRE header and a new outer IP delivery header, and the combined size of these two additions is what constitutes GRE's per-packet overhead. The base GRE header, as defined in RFC 2784 and used in its minimal, non-keyed, non-checksummed form (the default and most common deployment), is exactly 4 bytes in length, containing the flags/version field and the protocol type field identifying the encapsulated payload's ether type. Layered around that GRE header is a completely new outer IPv4 header, which itself consumes a standard 20 bytes, containing the tunnel source and destination addresses used for delivery across the underlying network. Adding these two components together — 4 bytes for the GRE header plus 20 bytes for the new outer IPv4 header — yields a total of exactly 24 bytes of overhead imposed on every encapsulated packet, which is precisely why Junos automatically sets the default protocol MTU on gr- tunnel interfaces to 1476 bytes (1500 minus 24) to prevent oversized, post-encapsulation packets from requiring fragmentation on a standard 1500-byte Ethernet path. The 20-byte figure alone describes only the new IP header in isolation and omits the GRE header itself, while 12 and 32 bytes do not correspond to any standard, non-keyed GRE encapsulation configuration and are included purely as plausible-looking distractors. Reference topics: Junos Enterprise Routing – Tunneling, GRE Header Overhead and MTU Planning.