Juniper JN0-364 Questions & Answers

This is a useful guard against OSPF designated router election, but it is not scoped to the observed IS-IS LSP database synchronization failure. An appropriate test would show that the two peers converge to consistent current LSP sequence information and compute the same intended topology reachability.

Check interface level settings on both ends during migration and alert on missing expected adjacency levels. That ongoing check is for IS-IS adjacency circuit level; it would not reliably detect recurrence of IS-IS LSP database synchronization. IS-IS LSP sequencing and sequence-number PDUs keep link-state databases synchronized; adjacency status alone does not ensure database parity. Applied here, the relevant facts are: After a transient LAN outage, peers disagree on LSP sequence numbers and one router temporarily lacks the new topology. The question asks which ongoing control would most directly detect or prevent the same failure from recurring.

Capture DIS election and pseudonode observations during shared LAN commissioning and role changes. That ongoing check is for IS-IS LAN designated intermediate system; it would not reliably detect recurrence of IS-IS LSP database synchronization. IS-IS LSP sequencing and sequence-number PDUs keep link-state databases synchronized; adjacency status alone does not ensure database parity.

Captured service frames show the expected outer provider tag and unchanged customer tag, with distinct customers isolated. It would validate a separate provider Q-in-Q tagging operation, not the change needed here. Confirm instead that the same VLAN numbers can exist where supported without unintended MAC or broadcast leakage across isolated virtual switches.

This measurement tests VSTP per-VLAN root choice; it cannot distinguish success from failure for the observed virtual-switch instance isolation condition. Virtual-switch routing instances provide separate bridge contexts; similar VLAN identifiers alone do not imply shared L2 forwarding.

Hosts receive the intended untagged frames and trunk links carry the specified VLAN tags with correct membership. It would validate a separate VLAN access trunk distinction operation, not the change needed here. Confirm instead that the same VLAN numbers can exist where supported without unintended MAC or broadcast leakage across isolated virtual switches.

The proposal changes OSPF hello and dead timers; that is not the failure isolated by the facts. It could leave OSPF interface metric selection unresolved even if its own test passed. OSPF chooses lowest-cost paths computed from link-state topology; a Full adjacency alone does not guarantee the desired route preference.

Set and test a coherent MED policy between comparable paths, acknowledging peer AS comparison behavior and upstream policies. Its normal acceptance signal would be comparably eligible paths carry intended MEDs and route selection in the agreed test case follows the planned preference. Here the deciding check is different: the best route's cumulative OSPF cost selects the approved path and changes predictably when the alternative fails.

Review interface network type and DR priorities, then plan election behavior with the existing DR and BDR state in mind. This addresses OSPF designated router election, but the reported symptoms arise from OSPF interface metric selection. For this case, verify instead that the best route's cumulative OSPF cost selects the approved path and changes predictably when the alternative fails.

Place each tenant's ports and VLANs in the intended virtual-switch context and verify independent bridge learning. Its normal acceptance signal would be the same VLAN numbers can exist where supported without unintended MAC or broadcast leakage across isolated virtual switches. Here the deciding check is different: hosts reach the expected IRB gateway and traffic between approved subnets is routed rather than bridged blindly.

Set access or trunk interface mode to match the attached device and approved VLAN membership. That could help in a case involving VLAN access trunk distinction. This failure instead depends on integrated routing and bridging; IRB provides an L3 interface for a Layer 2 VLAN bridge domain; MAC learning alone cannot perform inter-subnet routing.

The proposal changes IS-IS LSP database synchronization; that is not the failure isolated by the facts. It could leave integrated routing and bridging unresolved even if its own test passed. IRB provides an L3 interface for a Layer 2 VLAN bridge domain; MAC learning alone cannot perform inter-subnet routing.

This principle matters when troubleshooting static route next-hop resolution, but using it here mistakes a different failure mode for equal-cost forwarding flow hashing. The relevant distinction is: equal routing candidates do not prove the forwarding engine is using ECMP; Junos load-balancing policy and flow hashing determine installed next hops. Applied here, the relevant facts are: An operator enables multiple routes but expects alternating packets; the observed forwarding selection is stable per flow instead. The question asks which networking principle most accurately explains the observed failure.

This principle matters when troubleshooting filter-based forwarding table selection, but using it here mistakes a different failure mode for equal-cost forwarding flow hashing. The relevant distinction is: equal routing candidates do not prove the forwarding engine is using ECMP; Junos load-balancing policy and flow hashing determine installed next hops.

OSPF database description negotiation can reject incompatible interface MTUs even after hello packets establish initial communication. That describes OSPF MTU negotiation, whereas the observed symptoms are caused by equal-cost forwarding flow hashing; it does not predict the reported behavior.

Untagged frames map to the intended VLAN on both devices while explicitly tagged VLAN traffic remains isolated. That establishes native untagged VLAN drift rather than a repaired virtual-switch instance isolation path. The reported failure still requires this evidence: the same VLAN numbers can exist where supported without unintended MAC or broadcast leakage across isolated virtual switches.

The two peers progress through database synchronization to Full and agree on reachable link-state information. That establishes OSPF MTU negotiation rather than a repaired virtual-switch instance isolation path. The reported failure still requires this evidence: the same VLAN numbers can exist where supported without unintended MAC or broadcast leakage across isolated virtual switches.

The check is meaningful for provider bridging MTU overhead, but it does not prove that virtual-switch instance isolation was repaired. Virtual-switch routing instances provide separate bridge contexts; similar VLAN identifiers alone do not imply shared L2 forwarding.

This is a useful guard against IS-IS LSP database synchronization, but it is not scoped to the observed IS-IS wide metrics failure. An appropriate test would show that all participating nodes interpret intended link metrics consistently and select the expected least-cost paths.

Review IS-IS export policies against owner-approved prefix and origin criteria after service changes. The monitored boundary differs from IS-IS wide metrics, so the original weakness might reappear unnoticed. IS-IS metric encoding must support the configured value range; mixed or incompatible styles can alter SPF interpretation.

The control protects VRRP virtual gateway failover. It does not establish the ongoing IS-IS wide metrics behavior required in this network. IS-IS metric encoding must support the configured value range; mixed or incompatible styles can alter SPF interpretation.

Enable the supported BPDU protection behavior on designated edge ports so unexpected BPDUs trigger a controlled protective response. Its normal acceptance signal would be an unexpected BPDU causes the intended protective state and operations receive a traceable port event. Here the deciding check is different: adjacent devices report matching MST region configuration and VLANs map to the same intended instances.

Apply root protection on boundary designated ports where upstream superiority must be blocked and verify root placement. Its normal acceptance signal would be the approved root remains root despite inferior-site superior-BPDU injection, and the boundary behaves as designed. Here the deciding check is different: adjacent devices report matching MST region configuration and VLANs map to the same intended instances. Applied here, the relevant facts are: A provider access fabric changes its MST revision on only one device and behaves like a boundary instead of a single region. The question asks which focused engineering action would best correct the fault.

The proposal changes IS-IS TLV reachability; that is not the failure isolated by the facts. It could leave MSTP region consistency unresolved even if its own test passed. MSTP region identity depends on consistent name, revision, and VLAN mapping; mismatches create region boundaries.

Configure and verify the intended VSTP instance and per-VLAN root priorities for the affected VLANs. Its normal acceptance signal would be each VLAN's spanning-tree state selects its planned root and forwarding ports without creating a cross-VLAN loop. Here the deciding check is different: the approved root remains root despite inferior-site superior-BPDU injection, and the boundary behaves as designed.

Inspect the IS-IS link-state database and CSNP/PSNP exchange to resolve synchronization or flooding problems. This addresses IS-IS LSP database synchronization, but the reported symptoms arise from RSTP root protection. For this case, verify instead that the approved root remains root despite inferior-site superior-BPDU injection, and the boundary behaves as designed.

The proposal changes RSTP edge BPDU protection; that is not the failure isolated by the facts. It could leave RSTP root protection unresolved even if its own test passed. Root protection blocks acceptance of an unexpected superior root across designated boundary ports; it is not the same as BPDU edge protection.

Ethernet bridges learn destination forwarding from observed source MAC addresses; unstable topology can continually invalidate learned ports. That describes MAC address learning and moves, whereas the observed symptoms are caused by integrated routing and bridging; it does not predict the reported behavior.

Although filter-based forwarding table selection needs this consideration, the failure at issue has a different cause. IRB provides an L3 interface for a Layer 2 VLAN bridge domain; MAC learning alone cannot perform inter-subnet routing.

Junos interface VLAN tagging mode and logical-unit encapsulation must match received frame format for successful delivery. Those conditions do not account for the specific integrated routing and bridging problem reported by Everfield Rail.

Although provider Q-in-Q tagging needs this consideration, the failure at issue has a different cause. Virtual-switch routing instances provide separate bridge contexts; similar VLAN identifiers alone do not imply shared L2 forwarding.

This principle matters when troubleshooting OSPF point-to-point topology, but using it here mistakes a different failure mode for virtual-switch instance isolation. The relevant distinction is: virtual-switch routing instances provide separate bridge contexts; similar VLAN identifiers alone do not imply shared L2 forwarding.

Although VLAN access trunk distinction needs this consideration, the failure at issue has a different cause. Virtual-switch routing instances provide separate bridge contexts; similar VLAN identifiers alone do not imply shared L2 forwarding.