JN0-364 Sample Questions & Answers
Ten topics share equal weight: OSPF, IS-IS and BGP configuration, protocol-independent routing, Layer 2 bridging with VLANs, spanning-tree variants, MPLS, IPv6, tunneling, and configuring high availability.
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- Question 1Intermediate
Protocol-Independent Routing · Load balancing
A network administrator wants to ensure that traffic distributed across multiple equal-cost paths is load-balanced based on the IP headers rather than alternating individual packets to avoid out-of-order delivery. Which statement correctly describes load balancing behavior in Junos OS?
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Correct answer: C
In Junos OS, applying a load-balancing policy to the forwarding table using the 'export' statement under [edit routing-options forwarding-table] enables ECMP. By default, this implementation uses a hash algorithm based on IP headers (and optionally Layer 4 headers) to perform per-flow load balancing. This ensures that all packets belonging to the same flow take the same path, preventing out-of-order delivery issues common with strict per-packet load balancing.
- Question 2Beginner
Open Shortest Path First (OSPF) · Link-state advertisement (LSA) packet type
In an OSPF network with multiple areas, which Link-State Advertisement (LSA) type is generated by an Area Border Router (ABR) specifically to advertise the cost to reach an Autonomous System Boundary Router (ASBR)?
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Correct answer: B
A Type 4 LSA (ASBR Summary LSA) is generated by an ABR to advertise the presence and routing cost to an ASBR to routers in other areas. While Type 5 LSAs carry the actual external routes, routers outside the ASBR's area need the Type 4 LSA to know how to reach the ASBR itself, as Type 1 (Router) LSAs do not cross area boundaries.
- Question 3Intermediate
Open Shortest Path First (OSPF) · Adjacencies and neighbors
While troubleshooting an OSPF adjacency between two Juniper routers over a point-to-point link, an engineer notices that the neighbor state is stuck in ExStart/Exchange. What is the most likely cause of this issue?
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Correct answer: C
If an OSPF adjacency is stuck in the ExStart or Exchange state, the most common cause is an MTU mismatch between the two neighbors. During the ExStart/Exchange phase, routers exchange Database Description (DBD) packets. If the interface MTUs do not match, the routers will negotiate the master/slave relationship but fail to properly exchange the DBD packets, halting the adjacency process. Timer mismatches or area ID mismatches would prevent the adjacency from even reaching the Init/2-Way states.
- Question 4Beginner
Open Shortest Path First (OSPF) · Router ID
True or False: In Junos OS, if a router-id is explicitly configured under the [edit routing-options] hierarchy, it preempts any loopback interface IP address for OSPF router ID selection.
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Correct answer: A
True. In Junos OS, the OSPF Router ID is determined by a strict hierarchy. The highest priority is an explicitly configured router-id under [edit routing-options]. If not configured, it falls back to the primary IP address of the loopback interface (lo0). If no loopback is configured, it uses the highest IP address among the active interfaces.
- Question 5Advanced
Open Shortest Path First (OSPF) · OSPF area and router types
A service provider network connects to a newly acquired network that currently runs RIP. The engineering team redistributes the RIP routes into OSPF via an ASBR located in a Not-So-Stubby Area (NSSA) (Area 1). The OSPF domain has two ABRs (ABR-1 and ABR-2) connecting Area 1 to the Backbone (Area 0).
To ensure optimal routing without loops, how does OSPF handle the external routes generated within Area 1 when advertising them to Area 0?
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Correct answer: C
In an OSPF NSSA, the ASBR injects external routes as Type 7 LSAs, because Type 5 LSAs are not allowed in stub-like areas. When these Type 7 LSAs reach the ABRs, they must be translated to Type 5 LSAs to be injected into the backbone (Area 0). To prevent routing loops and duplicate LSA flooding, OSPF dictates that if multiple ABRs connect an NSSA to the backbone, only the ABR with the highest Router ID performs the Type 7 to Type 5 translation.
graph LR Ext[External RIP Network] -->|Redistribute| ASBR[ASBR] ASBR -->|Type 7 LSA| ABR1[ABR-1 Router ID: 1.1.1.1] ASBR -->|Type 7 LSA| ABR2[ABR-2 Router ID: 2.2.2.2] subgraph NSSA Area 1 ASBR end ABR1 -.->|Blocked| BB[Area 0 Backbone] ABR2 -->|Translates to Type 5 LSA| BB - Question 6Intermediate
Intermediate System to Intermediate System (IS-IS) · Designated intermediate system (DIS)
Which statement correctly describes the Designated Intermediate System (DIS) election process in IS-IS compared to the Designated Router (DR) election in OSPF?
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Correct answer: B
Unlike OSPF, where the DR role is non-preemptive (to ensure stability), the IS-IS DIS election is preemptive. If a new router with a higher priority (or higher MAC address if priorities tie) joins the broadcast segment, it will immediately assume the DIS role. Additionally, IS-IS does not elect a Backup DIS (BDIS), whereas OSPF elects a BDR.
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