Juniper JN0-364 Questions & Answers

This principle matters when troubleshooting IS-IS L1 and L2 reachability, but using it here mistakes a different failure mode for IS-IS TLV reachability. The relevant distinction is: IS-IS uses TLVs inside its PDUs to encode prefix and protocol capabilities; adjacency alone is not proof of expected reachability advertisements. Applied here, the relevant facts are: Two routers form an IS-IS adjacency but IPv6 destinations are missing because the required address-family reachability information is not advertised. The question asks which networking principle most accurately explains the observed failure.

This principle matters when troubleshooting OSPF interface metric selection, but using it here mistakes a different failure mode for IS-IS TLV reachability. The relevant distinction is: IS-IS uses TLVs inside its PDUs to encode prefix and protocol capabilities; adjacency alone is not proof of expected reachability advertisements.

The IS-IS NET encodes area membership and system identity, which must be consistent with the planned level and unique per node. Those conditions do not account for the specific IS-IS TLV reachability problem reported by Juniper Glen Telecom.

Capture representative stacked-label packets and verify transport-versus-service label parsing in acceptance tests. The monitored boundary differs from routing instance separation, so the original weakness might reappear unnoticed. Routing instances maintain separate routing and forwarding contexts; entries in one RIB do not automatically appear in another.

Alert when the required static route becomes hidden or its next hop stops resolving, and validate reachability before committing changes. That ongoing check is for static route next-hop resolution; it would not reliably detect recurrence of routing instance separation. Routing instances maintain separate routing and forwarding contexts; entries in one RIB do not automatically appear in another.

This is a useful guard against martian source address rejection, but it is not scoped to the observed routing instance separation failure. An appropriate test would show that the affected customer's lookup uses the intended instance RIB and reaches only the destinations deliberately made available to that instance.

The check is meaningful for BGP local preference, but it does not prove that BGP ASN and OPEN negotiation was repaired. BGP peers validate AS identity during OPEN negotiation; transport reachability by itself does not establish a valid BGP session.

The intended multi-hop peer establishes while IP reachability and any required loopback-source configuration are correct. It would validate a separate EBGP multihop reachability operation, not the change needed here. Confirm instead that the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

Neighbor state and system IDs show unique routers, and Level 1 adjacency establishes only among compatible area peers. That establishes IS-IS NET and system ID rather than a repaired BGP ASN and OPEN negotiation path. The reported failure still requires this evidence: the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

OSPFv3 provides OSPF routing for IPv6; successful IPv4 OSPFv2 peering does not establish an IPv6 adjacency. Those conditions do not account for the specific multiprotocol BGP IPv6 AFI problem reported by Unionpoint Mobile.

IS-IS can carry IPv6 topology and prefix information using appropriate TLVs; an IPv4 route table is not a substitute. Those conditions do not account for the specific multiprotocol BGP IPv6 AFI problem reported by Unionpoint Mobile.

OSPF uses the router ID to identify LSA originators; duplicate or unstable IDs undermine link-state identity. That describes stable OSPF router identifier, whereas the observed symptoms are caused by multiprotocol BGP IPv6 AFI; it does not predict the reported behavior.

Add an approved encryption layer such as IPsec when confidentiality is required, while retaining GRE only if needed for routing encapsulation. That could help in a case involving GRE confidentiality limitation. This failure instead depends on GRE tunnel path MTU; GRE adds header bytes, reducing effective payload MTU across an unchanged underlay path.

Give each router a unique system ID and a NET whose area portion matches intended Level 1 membership. Its normal acceptance signal would be neighbor state and system IDs show unique routers, and Level 1 adjacency establishes only among compatible area peers. Here the deciding check is different: maximum expected encapsulated packets cross the tunnel without fragmentation blackholes or oversized drop counters.

The proposal changes GRE endpoint underlay routing; that is not the failure isolated by the facts. It could leave GRE tunnel path MTU unresolved even if its own test passed. GRE adds header bytes, reducing effective payload MTU across an unchanged underlay path.

The check is meaningful for MPLS label push swap pop, but it does not prove that penultimate hop popping was repaired. Penultimate-hop popping can remove an outer transport label before the egress, reducing egress label processing.

The check is meaningful for MPLS label stack bottom bit, but it does not prove that penultimate hop popping was repaired. Penultimate-hop popping can remove an outer transport label before the egress, reducing egress label processing.

The check is meaningful for GRE confidentiality limitation, but it does not prove that penultimate hop popping was repaired. Penultimate-hop popping can remove an outer transport label before the egress, reducing egress label processing.

IRB provides an L3 interface for a Layer 2 VLAN bridge domain; MAC learning alone cannot perform inter-subnet routing. Those conditions do not account for the specific virtual-switch instance isolation problem reported by Elmbridge Networks.

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 virtual-switch instance isolation; it does not predict the reported behavior.

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 virtual-switch instance isolation problem reported by Elmbridge Networks.

Apply and verify the appropriate BGP community marking and matching terms on approved routes at the correct policy boundary. Its normal acceptance signal would be advertised routes carry the intended community and the relevant neighbor policy matches those routes as designed. Here the deciding check is different: the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

Inspect the forwarding lookup in the correct routing instance and apply explicit, authorized route sharing only where required. This addresses routing instance separation, but the reported symptoms arise from BGP ASN and OPEN negotiation. For this case, verify instead that the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

Fix internal next-hop reachability or use appropriate next-hop handling on the egress boundary, then confirm usable BGP forwarding. That could help in a case involving BGP next-hop reachability. This failure instead depends on BGP ASN and OPEN negotiation; BGP peers validate AS identity during OPEN negotiation; transport reachability by itself does not establish a valid BGP session.

Only approved prefixes are advertised to or accepted from the intended neighbor, as confirmed by received and advertised route views. It would validate a separate BGP import export control operation, not the change needed here. Confirm instead that the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

Comparably eligible paths carry intended MEDs and route selection in the agreed test case follows the planned preference. That establishes BGP MED neighbor consideration rather than a repaired BGP ASN and OPEN negotiation path. The reported failure still requires this evidence: the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

The broadcast segment has the planned DR and BDR and expected adjacency states after a controlled election event. It would validate a separate OSPF designated router election operation, not the change needed here. Confirm instead that the peer moves to Established with the agreed local and remote AS values and appropriate session messages.

Monitor high-frequency MAC moves and correlate them with spanning-tree and bridge-interface events. That ongoing check is for MAC address learning and moves; it would not reliably detect recurrence of RSTP alternate port reconvergence. RSTP port roles and rapid state transitions support fast loop-free reconvergence, unlike simply forcing all redundant ports forwarding.

Audit which ports are true edges and test protective action when a simulated switch sends a BPDU. That ongoing check is for RSTP edge BPDU protection; it would not reliably detect recurrence of RSTP alternate port reconvergence. RSTP port roles and rapid state transitions support fast loop-free reconvergence, unlike simply forcing all redundant ports forwarding.

The control protects MSTP region consistency. It does not establish the ongoing RSTP alternate port reconvergence behavior required in this network. RSTP port roles and rapid state transitions support fast loop-free reconvergence, unlike simply forcing all redundant ports forwarding.

Review per-link reserved and unreserved bandwidth before creating or resizing TE tunnels. That ongoing check is for RSVP path bandwidth admission; it would not reliably detect recurrence of aggregate route contributor. An aggregate route is conditional on active contributing routes and normally uses a discard or reject next hop to avoid creating a forwarding loop.

Continuously compare generated route eligibility and effective next hop against the approved regional reachability plan. The monitored boundary differs from aggregate route contributor, so the original weakness might reappear unnoticed. An aggregate route is conditional on active contributing routes and normally uses a discard or reject next hop to avoid creating a forwarding loop.

Validate VRF-specific route tables and access boundaries after all cross-instance policy changes. That ongoing check is for routing instance separation; it would not reliably detect recurrence of aggregate route contributor. An aggregate route is conditional on active contributing routes and normally uses a discard or reject next hop to avoid creating a forwarding loop.