Juniper JN0-650 Practice Test 51
Question 500
A replacement OSPF peer stops at Exchange after previously becoming Full. Which technical principle BEST explains the OSPF neighbor state troubleshooting workflow decision?
- ECMP commonly hashes traffic flows rather than balancing individual packets deterministically.
- Two-Way may be normal between DROther neighbors while Exchange stuck indicates database issues.
- OSPF interarea summarization originates at area boundaries with reachability tradeoffs.
- OSPF stub areas restrict external AS-external advertisements and require compatible area flags.
Explanation
Correct Answer
B:Two-Way may be normal between DROther neighbors while Exchange stuck indicates database issues. In this situation, the relevant action is to interpret neighbor state relative to network type and compare timers MTU and authentication.
Incorrect Answers
A:ECMP commonly hashes traffic flows rather than balancing individual packets deterministically. That principle is related to BGP ECMP per-flow hashing, not the main OSPF neighbor state troubleshooting workflow choice. Treating every Two-Way adjacency as a fatal database synchronization failure causes unnecessary changes.
C:OSPF interarea summarization originates at area boundaries with reachability tradeoffs. That principle is related to OSPF interarea route summarization, not the main OSPF neighbor state troubleshooting workflow choice. Treating every Two-Way adjacency as a fatal database synchronization failure causes unnecessary changes.
D:OSPF stub areas restrict external AS-external advertisements and require compatible area flags. That principle is related to OSPF stub area external LSA suppression, not the main OSPF neighbor state troubleshooting workflow choice. Treating every Two-Way adjacency as a fatal database synchronization failure causes unnecessary changes.
Question 501
A remote switch unregisters a dynamically learned VLAN during an upstream port event. Which technical principle BEST explains the MVRP static versus dynamic registration decision?
- PIM-SM can transition from shared RP tree to a source shortest-path tree.
- Private VLAN community ports have scoped peer reachability and promiscuous ports serve shared resources.
- BPDU protection blocks unexpected spanning-tree participation at designated access edges.
- MVRP learned registrations have different lifecycle from explicitly configured static VLAN memberships.
Explanation
Correct Answer
D:MVRP learned registrations have different lifecycle from explicitly configured static VLAN memberships. In this situation, the relevant action is to combine required static VLAN membership with deliberate dynamic registration policy.
Incorrect Answers
A:PIM-SM can transition from shared RP tree to a source shortest-path tree. That principle is related to ASM shared tree versus SPT switchover, not the main MVRP static versus dynamic registration choice. Assuming a learned VLAN is permanently present can break traffic after withdrawals.
B:Private VLAN community ports have scoped peer reachability and promiscuous ports serve shared resources. That principle is related to Private VLAN community and promiscuous roles, not the main MVRP static versus dynamic registration choice. Assuming a learned VLAN is permanently present can break traffic after withdrawals.
C:BPDU protection blocks unexpected spanning-tree participation at designated access edges. That principle is related to BPDU protection on access edges, not the main MVRP static versus dynamic registration choice. Assuming a learned VLAN is permanently present can break traffic after withdrawals.
Question 502
Two ASBRs advertise the same external route and different internal distances affect path choice. Which configuration or operational step BEST meets the stated requirement?
- Configure matching supported OSPF authentication parameters on both neighbors.
- Choose an intentional OSPF external metric type and test ASBR reachability assumptions.
- Increase a LAN VLAN ID and expect it to change the OSPF external metric type.
- Apply a guarded OSPFv3 export policy matching the correct inet6 source and prefix.
Explanation
Correct Answer
B:Choose an intentional OSPF external metric type and test ASBR reachability assumptions. OSPF E1 includes internal cost to ASBR whereas E2 comparison primarily uses external metric. The expected validation is that the preferred external route follows correct E1 total metric or E2 selection rules.
Incorrect Answers
A:Configure matching supported OSPF authentication parameters on both neighbors. This addresses OSPF authentication key or algorithm rather than the required OSPF external type-one versus type-two metrics decision. OSPF E1 includes internal cost to ASBR whereas E2 comparison primarily uses external metric.
C:Increase a LAN VLAN ID and expect it to change the OSPF external metric type. This is a risky or ineffective shortcut for OSPF external type-one versus type-two metrics. Treating E1 and E2 as interchangeable can send traffic over an unsuitable exit.
D: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 OSPF external type-one versus type-two metrics decision. OSPF E1 includes internal cost to ASBR whereas E2 comparison primarily uses external metric.
Question 503
During an operational risk review, this situation is reported: A team expects packet-by-packet round robin across BGP equal-cost interfaces. If the underlying control is neglected, which failure would MOST directly follow?
- Predicting equal utilization for a single heavy flow misunderstands per-flow selection.
- An overly general term can prevent subsequent protective terms from being reached.
- Excessive stale retention after a genuine failure can blackhole traffic.
- A healthy IPv4 neighbor is not proof of IPv6 adjacency or prefix reachability.
Explanation
Correct Answer
A:Predicting equal utilization for a single heavy flow misunderstands per-flow selection. ECMP commonly hashes traffic flows rather than balancing individual packets deterministically. A useful corrective investigation is to compare forwarding table and multiple test flow distribution.
Incorrect Answers
B:An overly general term can prevent subsequent protective terms from being reached. This is a Junos BGP policy term matching failure pattern, not the primary BGP ECMP per-flow hashing failure in this case. ECMP commonly hashes traffic flows rather than balancing individual packets deterministically.
C:Excessive stale retention after a genuine failure can blackhole traffic. This is a BGP graceful restart session continuity failure pattern, not the primary BGP ECMP per-flow hashing failure in this case. ECMP commonly hashes traffic flows rather than balancing individual packets deterministically.
D:A healthy IPv4 neighbor is not proof of IPv6 adjacency or prefix reachability. This is a OSPFv2 versus OSPFv3 operations failure pattern, not the primary BGP ECMP per-flow hashing failure in this case. ECMP commonly hashes traffic flows rather than balancing individual packets deterministically.
Question 504
Congestion should drop less important traffic before delay-sensitive or protected flows. Which configuration or operational step BEST meets the stated requirement?
- Configure supported IEEE 802.1p rewrite mapping at the Ethernet egress boundary.
- Assign deliberate PLP values through classification or policing policy.
- Set IP TTL to a high value and assume packet loss priority becomes low.
- Configure a supported traffic policer with appropriate rate and burst allowance.
Explanation
Correct Answer
B:Assign deliberate PLP values through classification or policing policy. Packet loss priority influences drop likelihood independent of forwarding class alone. The expected validation is that congestion accounting distinguishes low-PLP and high-PLP traffic as intended.
Incorrect Answers
A:Configure supported IEEE 802.1p rewrite mapping at the Ethernet egress boundary. This addresses IEEE 802.1p CoS rewrite on Ethernet rather than the required Packet loss priority PLP marking decision. Packet loss priority influences drop likelihood independent of forwarding class alone.
C:Set IP TTL to a high value and assume packet loss priority becomes low. This is a risky or ineffective shortcut for Packet loss priority PLP marking. Treating every packet as identical PLP may defeat differentiated congestion policy.
D:Configure a supported traffic policer with appropriate rate and burst allowance. This addresses Junos ingress policer rate limit rather than the required Packet loss priority PLP marking decision. Packet loss priority influences drop likelihood independent of forwarding class alone.
Question 505
A broad Layer 2 tunnel unexpectedly carries provider-facing LLDP messages to a customer. Select TWO statements that correctly combine the L2PT protocol selection and isolation implementation, its evidence, or its governing principle.
- Configure supported VLAN stacking with a service outer tag and preserve customer inner tags.
- Select explicitly supported customer protocols and enforce L2PT boundaries.
- Combine required static VLAN membership with deliberate dynamic registration policy.
- Intended customer control frames cross the service without exposing provider control state.
- Tunnel every provider management control packet to all customers as a safe default.
Explanation
Correct Answers
B:Select explicitly supported customer protocols and enforce L2PT boundaries. This is the intended implementation action for L2PT protocol selection and isolation.
D:Intended customer control frames cross the service without exposing provider control state. This is direct observable evidence for L2PT protocol selection and isolation.
Incorrect Answers
A:Configure supported VLAN stacking with a service outer tag and preserve customer inner tags. This belongs to QinQ service VLAN outer tag, not the specified L2PT protocol selection and isolation operation. L2PT should scope control-protocol tunneling to intended customer Ethernet boundaries.
C:Combine required static VLAN membership with deliberate dynamic registration policy. This belongs to MVRP static versus dynamic registration, not the specified L2PT protocol selection and isolation operation. L2PT should scope control-protocol tunneling to intended customer Ethernet boundaries.
E:Tunnel every provider management control packet to all customers as a safe default. This would not be an appropriate L2PT protocol selection and isolation decision. Overbroad tunneling may couple independent customer and provider control planes.
Question 506
A helpdesk ticket reports intermittent wired access on one switch interface. After deploying the recommended Junos Layer 2 authentication session monitoring change, which result MOST directly verifies success?
- Authenticated users enter the intended authorized VLAN while rejected users do not.
- Session logs identify the failing exchange or authorized role without broad policy bypass.
- Multicast frames reach receiver ports instead of every port by default.
- Guests receive only allowed connectivity and protected subnets stay unreachable.
Explanation
Correct Answer
B:Session logs identify the failing exchange or authorized role without broad policy bypass. This is the directly observable outcome for Junos Layer 2 authentication session monitoring. Authentication monitoring must inspect credentials authorization and port state separately.
Incorrect Answers
A:Authenticated users enter the intended authorized VLAN while rejected users do not. This validates Dynamic VLAN assignment from RADIUS but does not directly demonstrate the required Junos Layer 2 authentication session monitoring result. Authentication monitoring must inspect credentials authorization and port state separately.
C:Multicast frames reach receiver ports instead of every port by default. This validates IGMP snooping access-port replication but does not directly demonstrate the required Junos Layer 2 authentication session monitoring result. Authentication monitoring must inspect credentials authorization and port state separately.
D:Guests receive only allowed connectivity and protected subnets stay unreachable. This validates Guest VLAN for unauthenticated clients but does not directly demonstrate the required Junos Layer 2 authentication session monitoring result. Authentication monitoring must inspect credentials authorization and port state separately.
Question 507
During an operational risk review, this situation is reported: A route reflector fails to propagate one client route because client and nonclient roles are wrong. If the underlying control is neglected, which failure would MOST directly follow?
- Exporting internal tags to a peer may disclose internal routing policy semantics.
- Unbounded high-priority traffic can starve nonpriority queues.
- Incorrect reflection topology can hide otherwise valid internal paths.
- Damping critical destinations without review can prolong customer downtime.
Explanation
Correct Answer
C:Incorrect reflection topology can hide otherwise valid internal paths. BGP route reflection reduces iBGP full-mesh needs using originator and cluster loop controls. A useful corrective investigation is to inspect reflected path originator ID cluster list and neighbor client roles.
Incorrect Answers
A:Exporting internal tags to a peer may disclose internal routing policy semantics. This is a BGP communities match and deletion failure pattern, not the primary BGP route reflection cluster failure in this case. BGP route reflection reduces iBGP full-mesh needs using originator and cluster loop controls.
B:Unbounded high-priority traffic can starve nonpriority queues. This is a Scheduler strict priority and starvation failure pattern, not the primary BGP route reflection cluster failure in this case. BGP route reflection reduces iBGP full-mesh needs using originator and cluster loop controls.
D:Damping critical destinations without review can prolong customer downtime. This is a BGP route damping flap penalty failure pattern, not the primary BGP route reflection cluster failure in this case. BGP route reflection reduces iBGP full-mesh needs using originator and cluster loop controls.
Question 508
A policer drops valid traffic because committed burst settings are unrealistic. Which technical principle BEST explains the Junos ingress policer rate limit decision?
- Shaping delays packets to smooth egress rate while policing meters and may drop.
- A policer meters traffic and may drop or remark traffic exceeding its limits.
- Junos rewrite rules use internal forwarding class and PLP to set outbound header bits.
- eBGP multihop and local-address controls align transport endpoints and TTL.
Explanation
Correct Answer
B:A policer meters traffic and may drop or remark traffic exceeding its limits. In this situation, the relevant action is to configure a supported traffic policer with appropriate rate and burst allowance.
Incorrect Answers
A:Shaping delays packets to smooth egress rate while policing meters and may drop. That principle is related to Junos egress shaping rate, not the main Junos ingress policer rate limit choice. Wrong burst values can create unnecessary packet loss for permitted applications.
C:Junos rewrite rules use internal forwarding class and PLP to set outbound header bits. That principle is related to DSCP egress rewrite rules, not the main Junos ingress policer rate limit choice. Wrong burst values can create unnecessary packet loss for permitted applications.
D:EBGP multihop and local-address controls align transport endpoints and TTL. That principle is related to BGP loopback peering and multihop, not the main Junos ingress policer rate limit choice. Wrong burst values can create unnecessary packet loss for permitted applications.
Question 509
A user device bypasses 802.1X because a permissive MAC fallback runs first. Which next investigation or correction is MOST appropriate?
- Review session timers and test role change after reauthentication.
- Allow failed EAP authentication to receive unrestricted MAC authorization automatically.
- Test authorized and unauthorized MACs behind the same physical port.
- Test valid and invalid 802.1X plus MAC credentials across both endpoint classes.
Explanation
Correct Answer
D:Test valid and invalid 802.1X plus MAC credentials across both endpoint classes. This checks whether a proper 802.1X user receives employee access while device fallback remains limited.
Incorrect Answers
A:Review session timers and test role change after reauthentication. That check applies chiefly to 802.1X periodic reauthentication, not the current 802.1X versus MAC RADIUS method priority issue. Multiple authentication methods must be composed without creating a bypass path.
B:Allow failed EAP authentication to receive unrestricted MAC authorization automatically. That bypass leaves the 802.1X versus MAC RADIUS method priority issue unresolved. Uncontrolled method fallback can turn a stronger supplicant policy into a weak MAC-only policy.
C:Test authorized and unauthorized MACs behind the same physical port. That check applies chiefly to 802.1X multi-supplicant port control, not the current 802.1X versus MAC RADIUS method priority issue. Multiple authentication methods must be composed without creating a bypass path.
Question 510
One anycast-RP node fails and multicast should continue through an alternate active node. Which next investigation or correction is MOST appropriate?
- Inspect show pim rps and multicast route shared-tree state.
- Replace RP configuration with an ordinary Ethernet anycast MAC and assume PIM state synchronizes.
- Test loss of one RP while checking source registration and receiver delivery.
- Review RP election discovery information and group-range reachability.
Explanation
Correct Answer
C:Test loss of one RP while checking source registration and receiver delivery. This checks whether receivers continue forwarding through the surviving RP without changing group configuration.
Incorrect Answers
A:Inspect show pim rps and multicast route shared-tree state. That check applies chiefly to PIM sparse-mode RP shared tree, not the current Anycast RP with shared address issue. Anycast RP can present one logical RP address across multiple physical routers.
B:Replace RP configuration with an ordinary Ethernet anycast MAC and assume PIM state synchronizes. That bypass leaves the Anycast RP with shared address issue unresolved. Identical RP addresses without source-state coordination can break ASM reachability.
D:Review RP election discovery information and group-range reachability. That check applies chiefly to PIM RP discovery and bootstrap mapping, not the current Anycast RP with shared address issue. Anycast RP can present one logical RP address across multiple physical routers.
