Juniper JN0-650 Practice Test 18
Question 170
Two area-zero routers on an Ethernet link stay in Init because received Hellos list no reciprocal router ID. Which configuration or operational step BEST meets the stated requirement?
- Apply a guarded OSPFv3 export policy matching the correct inet6 source and prefix.
- Choose an intentional OSPF external metric type and test ASBR reachability assumptions.
- Change only the router ID and claim incompatible timer settings will be ignored.
- Compare Hello packets area ID intervals and neighbor states before changing interface OSPF settings.
Explanation
Correct Answer
D:Compare Hello packets area ID intervals and neighbor states before changing interface OSPF settings. OSPF neighbors exchange compatible Hellos before database synchronization. The expected validation is that a full adjacency forms after bidirectional Hellos and compatible timers are observed.
Incorrect Answers
A:Apply a guarded OSPFv3 export policy matching the correct inet6 source and prefix. This addresses OSPFv3 routing policy for external IPv6 rather than the required OSPFv2 Hello and Dead timer adjacency decision. OSPF neighbors exchange compatible Hellos before database synchronization.
B:Choose an intentional OSPF external metric type and test ASBR reachability assumptions. This addresses OSPF external type-one versus type-two metrics rather than the required OSPFv2 Hello and Dead timer adjacency decision. OSPF neighbors exchange compatible Hellos before database synchronization.
C:Change only the router ID and claim incompatible timer settings will be ignored. This is a risky or ineffective shortcut for OSPFv2 Hello and Dead timer adjacency. Mismatched Hello or Dead intervals block a reliable adjacency.
Question 171
During an operational risk review, this situation is reported: A WAN peer expects a traffic-entry preference but sees inconsistent MED attributes. If the underlying control is neglected, which failure would MOST directly follow?
- Incorrect reflection topology can hide otherwise valid internal paths.
- Confusing local preference with Junos route preference can produce wrong active-route reasoning.
- Assuming MED overrides every higher-priority BGP selection criterion leads to false expectations.
- Changing the switch IP address does not correct an endpoint access VLAN mismatch.
Explanation
Correct Answer
C:Assuming MED overrides every higher-priority BGP selection criterion leads to false expectations. MED is a nontransitive path attribute often compared between paths from the same neighboring AS. A useful corrective investigation is to inspect advertised BGP MED and compare upstream decision policy when accessible.
Incorrect Answers
A:Incorrect reflection topology can hide otherwise valid internal paths. This is a BGP route reflection cluster failure pattern, not the primary BGP MED inbound traffic hint failure in this case. MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
B:Confusing local preference with Junos route preference can produce wrong active-route reasoning. This is a BGP route preference versus OSPF failure pattern, not the primary BGP MED inbound traffic hint failure in this case. MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
D:Changing the switch IP address does not correct an endpoint access VLAN mismatch. This is a Ethernet access interface VLAN membership failure pattern, not the primary BGP MED inbound traffic hint failure in this case. MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
Question 172
Two leaf switches both start forwarding a segment intended for single-active behavior. Which technical principle BEST explains the EVPN single-active multihoming access mode decision?
- Routing policy must match the relevant address family as well as eligible source routes.
- Type3 IMET routes signal participation in an EVPN broadcast domain for BUM distribution.
- Single-active multihoming deliberately avoids parallel forwarding on a shared segment.
- ESI identifies a shared multihomed Ethernet segment to EVPN control plane.
Explanation
Correct Answer
C:Single-active multihoming deliberately avoids parallel forwarding on a shared segment. In this situation, the relevant action is to configure supported single-active EVPN multihoming and failover selection.
Incorrect Answers
A:Routing policy must match the relevant address family as well as eligible source routes. That principle is related to OSPFv3 routing policy for external IPv6, not the main EVPN single-active multihoming access mode choice. Enabling unintended all-active behavior can violate a single-active attachment design.
B:Type3 IMET routes signal participation in an EVPN broadcast domain for BUM distribution. That principle is related to EVPN Type3 IMET inclusive multicast routes, not the main EVPN single-active multihoming access mode choice. Enabling unintended all-active behavior can violate a single-active attachment design.
D:ESI identifies a shared multihomed Ethernet segment to EVPN control plane. That principle is related to Ethernet segment identifier ESI consistency, not the main EVPN single-active multihoming access mode choice. Enabling unintended all-active behavior can violate a single-active attachment design.
Question 173
Two all-active EVPN leaves receive the same multicast flood traffic for a shared access segment. Which configuration or operational step BEST meets the stated requirement?
- Configure matching supported Ethernet segment identifier and multihoming attachments.
- Configure supported single-active EVPN multihoming and failover selection.
- Validate supported DF election and its per-segment or VLAN role assignments.
- Select the OSPF DR and assume it automatically becomes EVPN DF for every Ethernet segment.
Explanation
Correct Answer
C:Validate supported DF election and its per-segment or VLAN role assignments. EVPN DF controls multihomed access delivery of broadcast unknown-unicast and multicast traffic. The expected validation is that only the authorized DF forwards designated BUM traffic toward the shared segment.
Incorrect Answers
A:Configure matching supported Ethernet segment identifier and multihoming attachments. This addresses Ethernet segment identifier ESI consistency rather than the required EVPN designated forwarder DF for BUM decision. EVPN DF controls multihomed access delivery of broadcast unknown-unicast and multicast traffic.
B:Configure supported single-active EVPN multihoming and failover selection. This addresses EVPN single-active multihoming access mode rather than the required EVPN designated forwarder DF for BUM decision. EVPN DF controls multihomed access delivery of broadcast unknown-unicast and multicast traffic.
D:Select the OSPF DR and assume it automatically becomes EVPN DF for every Ethernet segment. This is a risky or ineffective shortcut for EVPN designated forwarder DF for BUM. Incorrect DF state may duplicate BUM traffic or strand a segment after failure.
Question 174
A replacement switch uses a smaller routed interface MTU than the adjacent router. Which next investigation or correction is MOST appropriate?
- Collect show ospf neighbor detail and correlate state progression against network design.
- Compare export term counters originator LSDB and external destinations on a neighbor.
- Inspect detailed neighbor state and interface MTU on both systems.
- Clear every BGP session without evaluating the OSPF DBD packets.
Explanation
Correct Answer
C:Inspect detailed neighbor state and interface MTU on both systems. This checks whether database-description exchange completes and neighbor reaches Full.
Incorrect Answers
A:Collect show ospf neighbor detail and correlate state progression against network design. That check applies chiefly to OSPF neighbor state troubleshooting workflow, not the current OSPF interface MTU mismatch issue. OSPF database exchange can stall when peers disagree on interface MTU.
B:Compare export term counters originator LSDB and external destinations on a neighbor. That check applies chiefly to OSPF external export policy redistribution, not the current OSPF interface MTU mismatch issue. OSPF database exchange can stall when peers disagree on interface MTU.
D:Clear every BGP session without evaluating the OSPF DBD packets. That bypass leaves the OSPF interface MTU mismatch issue unresolved. DBD packet rejection can leave neighbors oscillating at ExStart or Exchange.
Question 175
A multicast source is reachable only through a preferred unicast IGP path. Which configuration or operational step BEST meets the stated requirement?
- Build supported anycast-RP reachability and synchronize source awareness as required.
- Align source reachability and any approved multicast RPF policy with actual topology.
- Troubleshoot source activity group membership RPF PIM joins and data packet counters in order.
- Increase IGMP membership duration to repair an unrelated reversed unicast route.
Explanation
Correct Answer
B:Align source reachability and any approved multicast RPF policy with actual topology. RPF uses source or RP reachability and can change when unicast routing changes. The expected validation is that incoming multicast packets arrive on the interface selected by a valid source route.
Incorrect Answers
A:Build supported anycast-RP reachability and synchronize source awareness as required. This addresses Anycast RP with shared address rather than the required Multicast source route policy and RPF decision. RPF uses source or RP reachability and can change when unicast routing changes.
C:Troubleshoot source activity group membership RPF PIM joins and data packet counters in order. This addresses Multicast troubleshooting separate control and data planes rather than the required Multicast source route policy and RPF decision. RPF uses source or RP reachability and can change when unicast routing changes.
D:Increase IGMP membership duration to repair an unrelated reversed unicast route. This is a risky or ineffective shortcut for Multicast source route policy and RPF. An unexpected source route preference may cause RPF failures after a control-plane change.
Question 176
During an operational risk review, this situation is reported: A distribution port blocks when superior BPDUs arrive from a downstream access switch. If the underlying control is neglected, which failure would MOST directly follow?
- Enabling it on legitimate interswitch links can unnecessarily disable useful uplinks.
- Broad first-match conditions can eclipse later VLAN classification terms.
- Allowing untrusted access switches to become STP root can shift and disrupt network paths.
- DBD packet rejection can leave neighbors oscillating at ExStart or Exchange.
Explanation
Correct Answer
C:Allowing untrusted access switches to become STP root can shift and disrupt network paths. Root protection guards designated bridge roles against unexpected root changes. A useful corrective investigation is to inspect root-protection state and spanning-tree topology events.
Incorrect Answers
A:Enabling it on legitimate interswitch links can unnecessarily disable useful uplinks. This is a BPDU protection on access edges failure pattern, not the primary Root protection on designated links failure in this case. Root protection guards designated bridge roles against unexpected root changes.
B:Broad first-match conditions can eclipse later VLAN classification terms. This is a Filter-based VLAN rule precedence failure pattern, not the primary Root protection on designated links failure in this case. Root protection guards designated bridge roles against unexpected root changes.
D:DBD packet rejection can leave neighbors oscillating at ExStart or Exchange. This is a OSPF interface MTU mismatch failure pattern, not the primary Root protection on designated links failure in this case. Root protection guards designated bridge roles against unexpected root changes.
Question 177
An IPv6 default learned from another protocol must be redistributed selectively. After deploying the recommended OSPFv3 routing policy for external IPv6 change, which result MOST directly verifies success?
- Remote IPv6 routers receive only the intended OSPFv3 external destinations.
- Neighbors learn intended external LSAs without importing restricted management networks.
- All approved phones receive adequate negotiated power without exceeding switch capacity.
- A full adjacency forms after bidirectional Hellos and compatible timers are observed.
Explanation
Correct Answer
A:Remote IPv6 routers receive only the intended OSPFv3 external destinations. This is the directly observable outcome for OSPFv3 routing policy for external IPv6. Routing policy must match the relevant address family as well as eligible source routes.
Incorrect Answers
B:Neighbors learn intended external LSAs without importing restricted management networks. This validates OSPF external export policy redistribution but does not directly demonstrate the required OSPFv3 routing policy for external IPv6 result. Routing policy must match the relevant address family as well as eligible source routes.
C:All approved phones receive adequate negotiated power without exceeding switch capacity. This validates PoE power budget switch capacity but does not directly demonstrate the required OSPFv3 routing policy for external IPv6 result. Routing policy must match the relevant address family as well as eligible source routes.
D:A full adjacency forms after bidirectional Hellos and compatible timers are observed. This validates OSPFv2 Hello and Dead timer adjacency but does not directly demonstrate the required OSPFv3 routing policy for external IPv6 result. Routing policy must match the relevant address family as well as eligible source routes.
Question 178
An edge policy uses community values to decide whether to advertise specific routes. Which technical principle BEST explains the BGP communities tagging routing intent decision?
- Junos routing policy evaluates ordered terms and control-flow actions.
- Junos route selection between protocols is not the same as BGP best-path selection.
- BGP communities carry policy metadata without directly supplying next-hop reachability.
- Per-VLAN STP compatibility depends on VLAN tagging and protocol expectations.
Explanation
Correct Answer
C:BGP communities carry policy metadata without directly supplying next-hop reachability. In this situation, the relevant action is to add approved BGP community tags and match them in explicit import or export policies.
Incorrect Answers
A:Junos routing policy evaluates ordered terms and control-flow actions. That principle is related to Junos BGP policy term matching, not the main BGP communities tagging routing intent choice. Marking a community without a matching policy may not change routing.
B:Junos route selection between protocols is not the same as BGP best-path selection. That principle is related to BGP route preference versus OSPF, not the main BGP communities tagging routing intent choice. Marking a community without a matching policy may not change routing.
D:Per-VLAN STP compatibility depends on VLAN tagging and protocol expectations. That principle is related to VSTP interoperation and VLAN tagging, not the main BGP communities tagging routing intent choice. Marking a community without a matching policy may not change routing.
Question 179
One copper link has wiring faults while data LEDs intermittently appear active. Which next investigation or correction is MOST appropriate?
- Create an OSPF neighbor statement and assume damaged copper pairs are repaired.
- Inspect LLDP-MED network policy fields and captured 802.1Q priority bits.
- Compare PoE state and cable diagnostics on known-good versus failing links.
- Verify phone tag IDs and PC untagged frames in a mirrored capture.
Explanation
Correct Answer
C:Compare PoE state and cable diagnostics on known-good versus failing links. This checks whether the phone powers reliably on the approved port with no short or overload alarms.
Incorrect Answers
A:Create an OSPF neighbor statement and assume damaged copper pairs are repaired. That bypass leaves the PoE fault isolation and cable pair issue unresolved. A physical pair or overload fault can stop power before any voice VLAN setup matters.
B:Inspect LLDP-MED network policy fields and captured 802.1Q priority bits. That check applies chiefly to LLDP-MED voice priority signaling, not the current PoE fault isolation and cable pair issue. PoE delivery requires compatible power sourcing and physical cable conditions.
D:Verify phone tag IDs and PC untagged frames in a mirrored capture. That check applies chiefly to Voice VLAN tagged versus PC data traffic, not the current PoE fault isolation and cable pair issue. PoE delivery requires compatible power sourcing and physical cable conditions.
Question 180
An import policy unexpectedly accepts a long private prefix because an early term matches broadly. Select TWO statements that correctly combine the Junos BGP policy term matching implementation, its evidence, or its governing principle.
- Only sanctioned routes pass the policy and term counters identify the decision.
- Put a filter name in the peer description and assume it becomes an active policy.
- Implement ordered Junos policy terms with prefix match and explicit accept or reject decisions.
- Restore valid next-hop reachability without indiscriminately accepting broken routes.
- Examine and apply origin attribute handling only within an intentional routing-policy decision.
Explanation
Correct Answers
A:Only sanctioned routes pass the policy and term counters identify the decision. This is direct observable evidence for Junos BGP policy term matching.
C:Implement ordered Junos policy terms with prefix match and explicit accept or reject decisions. This is the intended implementation action for Junos BGP policy term matching.
Incorrect Answers
B:Put a filter name in the peer description and assume it becomes an active policy. This would not be an appropriate Junos BGP policy term matching decision. An overly general term can prevent subsequent protective terms from being reached.
D:Restore valid next-hop reachability without indiscriminately accepting broken routes. This belongs to BGP next-hop reachability hidden route, not the specified Junos BGP policy term matching operation. Junos routing policy evaluates ordered terms and control-flow actions.
E:Examine and apply origin attribute handling only within an intentional routing-policy decision. This belongs to BGP origin attribute influence, not the specified Junos BGP policy term matching operation. Junos routing policy evaluates ordered terms and control-flow actions.
