Juniper JN0-650 Practice Test 65
Question 640
Two candidate routes exist but one fails import policy and another lacks a next hop. Which technical principle BEST explains the BGP hidden and rejected path diagnosis decision?
- Anycast RP can present one logical RP address across multiple physical routers.
- Communities can be selectively matched manipulated and stripped in routing policy.
- BGP neighbor state and route installation are separate control-plane gates.
- BGP origin distinguishes IGP EGP and incomplete values with limited relative ranking.
Explanation
Correct Answer
C:BGP neighbor state and route installation are separate control-plane gates. In this situation, the relevant action is to trace BGP received route status through import policy next-hop resolution and path eligibility.
Incorrect Answers
A:Anycast RP can present one logical RP address across multiple physical routers. That principle is related to Anycast RP with shared address, not the main BGP hidden and rejected path diagnosis choice. Treating peer Established as proof every received prefix is installed masks routing failures.
B:Communities can be selectively matched manipulated and stripped in routing policy. That principle is related to BGP communities match and deletion, not the main BGP hidden and rejected path diagnosis choice. Treating peer Established as proof every received prefix is installed masks routing failures.
D:BGP origin distinguishes IGP EGP and incomplete values with limited relative ranking. That principle is related to BGP origin attribute influence, not the main BGP hidden and rejected path diagnosis choice. Treating peer Established as proof every received prefix is installed masks routing failures.
Question 641
A provider changes its ASN and a previously stable BGP session stops opening. Which next investigation or correction is MOST appropriate?
- Inspect show route protocol bgp extensive for AS_PATH and hidden reason.
- Inspect show bgp neighbor last error and BGP OPEN notification fields.
- Inspect show route advertising-protocol BGP and remote policy confirmation if available.
- Change an OSPF cost and assume it repairs the remote AS mismatch.
Explanation
Correct Answer
B:Inspect show bgp neighbor last error and BGP OPEN notification fields. This checks whether bGP reaches Established with the expected local and remote ASN and prefix families.
Incorrect Answers
A:Inspect show route protocol bgp extensive for AS_PATH and hidden reason. That check applies chiefly to BGP AS_PATH loop prevention and length, not the current BGP eBGP peer AS and local identity issue. BGP OPEN exchange checks autonomous-system identity and capability compatibility.
C:Inspect show route advertising-protocol BGP and remote policy confirmation if available. That check applies chiefly to BGP AS path prepend outbound advertisement, not the current BGP eBGP peer AS and local identity issue. BGP OPEN exchange checks autonomous-system identity and capability compatibility.
D:Change an OSPF cost and assume it repairs the remote AS mismatch. That bypass leaves the BGP eBGP peer AS and local identity issue unresolved. Wrong peer-AS values cause BGP OPEN rejection despite TCP connectivity.
Question 642
A network engineer needs to distinguish EAP failure from a VLAN or transport problem. Which technical principle BEST explains the Junos Layer 2 authentication session monitoring decision?
- EVPN all-active multihoming can use parallel forwarding paths with designated loop protection.
- Authentication monitoring must inspect credentials authorization and port state separately.
- Guest VLAN authorizes limited access for eligible unauthenticated clients.
- MAC addresses can be imitated and are weaker credentials than authenticated EAP identities.
Explanation
Correct Answer
B:Authentication monitoring must inspect credentials authorization and port state separately. In this situation, the relevant action is to collect show dot1x interface and access session state plus relevant RADIUS logs.
Incorrect Answers
A:EVPN all-active multihoming can use parallel forwarding paths with designated loop protection. That principle is related to EVPN all-active multihoming forwarding, not the main Junos Layer 2 authentication session monitoring choice. Checking only link-up LED can miss failed 802.1X or RADIUS authorization.
C:Guest VLAN authorizes limited access for eligible unauthenticated clients. That principle is related to Guest VLAN for unauthenticated clients, not the main Junos Layer 2 authentication session monitoring choice. Checking only link-up LED can miss failed 802.1X or RADIUS authorization.
D:MAC addresses can be imitated and are weaker credentials than authenticated EAP identities. That principle is related to MAC RADIUS spoofing limitations, not the main Junos Layer 2 authentication session monitoring choice. Checking only link-up LED can miss failed 802.1X or RADIUS authorization.
Question 643
Different Junos routers use conflicting RP addresses for the same ASM range. After deploying the recommended Static RP mapping group range change, which result MOST directly verifies success?
- Every receiver-facing router resolves the same intended RP for each permitted group.
- (S,G) state forwards only the desired source without RP discovery for SSM.
- The BGP route becomes active after recursive next-hop resolution succeeds.
- The IGMP state records the intended source and excludes other senders.
Explanation
Correct Answer
A:Every receiver-facing router resolves the same intended RP for each permitted group. This is the directly observable outcome for Static RP mapping group range. RP mapping and unicast RP reachability are separate multicast requirements.
Incorrect Answers
B:(S,G) state forwards only the desired source without RP discovery for SSM. This validates SSM without rendezvous point but does not directly demonstrate the required Static RP mapping group range result. RP mapping and unicast RP reachability are separate multicast requirements.
C:The BGP route becomes active after recursive next-hop resolution succeeds. This validates BGP next-hop reachability hidden route but does not directly demonstrate the required Static RP mapping group range result. RP mapping and unicast RP reachability are separate multicast requirements.
D:The IGMP state records the intended source and excludes other senders. This validates IGMPv3 source include mode but does not directly demonstrate the required Static RP mapping group range result. RP mapping and unicast RP reachability are separate multicast requirements.
Question 644
An import from a connected route unexpectedly redistributes unrelated management prefixes. Which technical principle BEST explains the OSPF external export policy redistribution decision?
- Spanning tree chooses port roles to avoid loops while maintaining redundant paths.
- Junos OSPF export policies govern which eligible routes enter OSPF as externals.
- OSPF SPF selects lowest cumulative link cost subject to policy and availability.
- OSPFv3 separates neighbor topology information from IPv6 prefix dissemination.
Explanation
Correct Answer
B:Junos OSPF export policies govern which eligible routes enter OSPF as externals. In this situation, the relevant action is to attach an explicit OSPF export policy matching only approved active source routes.
Incorrect Answers
A:Spanning tree chooses port roles to avoid loops while maintaining redundant paths. That principle is related to MSTP root port and alternate path, not the main OSPF external export policy redistribution choice. An overly permissive export can leak private or unreachable prefixes across the domain.
C:OSPF SPF selects lowest cumulative link cost subject to policy and availability. That principle is related to OSPF path cost selection, not the main OSPF external export policy redistribution choice. An overly permissive export can leak private or unreachable prefixes across the domain.
D:OSPFv3 separates neighbor topology information from IPv6 prefix dissemination. That principle is related to OSPFv3 IPv6 prefix advertisement, not the main OSPF external export policy redistribution choice. An overly permissive export can leak private or unreachable prefixes across the domain.
Question 645
During an operational risk review, this situation is reported: Two candidate routes exist but one fails import policy and another lacks a next hop. If the underlying control is neglected, which failure would MOST directly follow?
- Treating peer Established as proof every received prefix is installed masks routing failures.
- Inserting prepends into all paths can cause unexpected global traffic shifts.
- Reusing an IPv4-only route filter can leave IPv6 export expectations unmet.
- No route-count guard can overwhelm route memory or control-plane processing.
Explanation
Correct Answer
A:Treating peer Established as proof every received prefix is installed masks routing failures. BGP neighbor state and route installation are separate control-plane gates. A useful corrective investigation is to inspect show route hidden extensive and relevant policy terms.
Incorrect Answers
B:Inserting prepends into all paths can cause unexpected global traffic shifts. This is a BGP AS path prepend outbound advertisement failure pattern, not the primary BGP hidden and rejected path diagnosis failure in this case. BGP neighbor state and route installation are separate control-plane gates.
C:Reusing an IPv4-only route filter can leave IPv6 export expectations unmet. This is a OSPFv3 routing policy for external IPv6 failure pattern, not the primary BGP hidden and rejected path diagnosis failure in this case. BGP neighbor state and route installation are separate control-plane gates.
D:No route-count guard can overwhelm route memory or control-plane processing. This is a BGP prefix-limit peer protection failure pattern, not the primary BGP hidden and rejected path diagnosis failure in this case. BGP neighbor state and route installation are separate control-plane gates.
Question 646
A branch OSPF area should avoid learning thousands of external type-5 LSAs. Which configuration or operational step BEST meets the stated requirement?
- Apply supported route policy at the correct Junos OSPF import or RIB-selection control.
- Configure only a BGP export policy and claim the OSPF area became stub.
- Configure compatible stub area attributes on all affected OSPF routers.
- Tune eligible OSPF interface priority and plan an explicit election event where required.
Explanation
Correct Answer
C:Configure compatible stub area attributes on all affected OSPF routers. OSPF stub areas restrict external AS-external advertisements and require compatible area flags. The expected validation is that the stub receives an appropriate default or interarea reachability without external type-5 flooding.
Incorrect Answers
A:Apply supported route policy at the correct Junos OSPF import or RIB-selection control. This addresses OSPF routing policy import filtering rather than the required OSPF stub area external LSA suppression decision. OSPF stub areas restrict external AS-external advertisements and require compatible area flags.
B:Configure only a BGP export policy and claim the OSPF area became stub. This is a risky or ineffective shortcut for OSPF stub area external LSA suppression. Mixing stub and normal-area settings prevents correct neighbor establishment.
D:Tune eligible OSPF interface priority and plan an explicit election event where required. This addresses OSPF designated router election broadcast LAN rather than the required OSPF stub area external LSA suppression decision. OSPF stub areas restrict external AS-external advertisements and require compatible area flags.
Question 647
IPv6 voice flows receive default queue treatment while IPv4 voice works. Which configuration or operational step BEST meets the stated requirement?
- Configure supported priority treatment with bounds and sufficient lower-class service.
- Modify IPv6 route preference and assume it sets the IPv6 DSCP classifier.
- Tune supported scheduler buffer sizes consistent with measured burst requirements.
- Apply appropriate supported IPv6 DSCP classification on the relevant ingress family.
Explanation
Correct Answer
D:Apply appropriate supported IPv6 DSCP classification on the relevant ingress family. Packet classification must account for the correct protocol header family. The expected validation is that authorized IPv4 and IPv6 voice receive equivalent intended forwarding-class treatment.
Incorrect Answers
A:Configure supported priority treatment with bounds and sufficient lower-class service. This addresses Scheduler strict priority and starvation rather than the required Junos IPv6 DSCP classifier family decision. Packet classification must account for the correct protocol header family.
B:Modify IPv6 route preference and assume it sets the IPv6 DSCP classifier. This is a risky or ineffective shortcut for Junos IPv6 DSCP classifier family. Assuming an IPv4-only classifier handles all IPv6 traffic may cause inconsistent QoS.
C:Tune supported scheduler buffer sizes consistent with measured burst requirements. This addresses Queue buffer-size allocation rather than the required Junos IPv6 DSCP classifier family decision. Packet classification must account for the correct protocol header family.
Question 648
A wrong ESI on one leaf makes the access segment appear as unrelated attachments. Which next investigation or correction is MOST appropriate?
- Set the same OSPF router ID and assume it creates a shared EVPN Ethernet segment.
- Inspect Ethernet segment state and EVPN ESI route fields on both leaves.
- Inspect active and standby Ethernet segment status during a link failover.
- Test link failure and traffic across both healthy peers while inspecting ES state.
Explanation
Correct Answer
B:Inspect Ethernet segment state and EVPN ESI route fields on both leaves. This checks whether peers agree on a common Ethernet segment and relevant EVPN ES routes.
Incorrect Answers
A:Set the same OSPF router ID and assume it creates a shared EVPN Ethernet segment. That bypass leaves the Ethernet segment identifier ESI consistency issue unresolved. Different ESI values on supposed peers can defeat multihoming loop protection.
C:Inspect active and standby Ethernet segment status during a link failover. That check applies chiefly to EVPN single-active multihoming access mode, not the current Ethernet segment identifier ESI consistency issue. ESI identifies a shared multihomed Ethernet segment to EVPN control plane.
D:Test link failure and traffic across both healthy peers while inspecting ES state. That check applies chiefly to EVPN all-active multihoming forwarding, not the current Ethernet segment identifier ESI consistency issue. ESI identifies a shared multihomed Ethernet segment to EVPN control plane.
Question 649
A network team needs to distinguish class-mapping errors from physical link saturation. Which technical principle BEST explains the CoS end-to-end verification of drop behavior decision?
- EVPN all-active multihoming can use parallel forwarding paths with designated loop protection.
- Egress buffers absorb short bursts but cannot compensate for persistent overload.
- Successful CoS needs consistent ingress classification egress scheduling and congestion management.
- Multifield classification can use packet fields beyond preexisting DSCP markings.
Explanation
Correct Answer
C:Successful CoS needs consistent ingress classification egress scheduling and congestion management. In this situation, the relevant action is to combine per-class classification queue occupancy drop and packet-marking evidence across bottlenecks.
Incorrect Answers
A:EVPN all-active multihoming can use parallel forwarding paths with designated loop protection. That principle is related to EVPN all-active multihoming forwarding, not the main CoS end-to-end verification of drop behavior choice. Inspecting only a configured class name can hide actual drops and misclassification.
B:Egress buffers absorb short bursts but cannot compensate for persistent overload. That principle is related to Queue buffer-size allocation, not the main CoS end-to-end verification of drop behavior choice. Inspecting only a configured class name can hide actual drops and misclassification.
D:Multifield classification can use packet fields beyond preexisting DSCP markings. That principle is related to Junos multifield firewall filter classification, not the main CoS end-to-end verification of drop behavior choice. Inspecting only a configured class name can hide actual drops and misclassification.
Question 650
A client leaves a video group yet traffic persists to its access port. Which technical principle BEST explains the IGMPv2 membership report and leave decision?
- IPv4 multicast destination ranges are group identifiers rather than ordinary host addresses.
- IPv6 multicast uses ff00::/8 scoped addressing separate from IPv4 group syntax.
- IGMP expresses host interest in groups while routing protocols move traffic between subnets.
- 802.1X host-mode behavior controls whether access applies per endpoint or per port.
Explanation
Correct Answer
C:IGMP expresses host interest in groups while routing protocols move traffic between subnets. In this situation, the relevant action is to verify IGMPv2 membership joins leaves and querier operation for the intended subnet.
Incorrect Answers
A:IPv4 multicast destination ranges are group identifiers rather than ordinary host addresses. That principle is related to IPv4 multicast group address versus unicast, not the main IGMPv2 membership report and leave choice. Treating IGMP as an interrouter PIM replacement prevents routed multicast delivery.
B:IPv6 multicast uses ff00::/8 scoped addressing separate from IPv4 group syntax. That principle is related to IPv6 multicast scope and group use, not the main IGMPv2 membership report and leave choice. Treating IGMP as an interrouter PIM replacement prevents routed multicast delivery.
D:802.1X host-mode behavior controls whether access applies per endpoint or per port. That principle is related to 802.1X multi-supplicant port control, not the main IGMPv2 membership report and leave choice. Treating IGMP as an interrouter PIM replacement prevents routed multicast delivery.
