Juniper JN0-650 Practice Test 28
Question 270
Two switches with identical MST instance IDs operate as different MST regions. Which configuration or operational step BEST meets the stated requirement?
- Change the BGP local AS to make mismatched MST region digests agree.
- Align MSTP region name revision and VLAN-to-instance mapping across intended peers.
- Configure supported Layer 2 Protocol Tunneling for selected customer control protocols.
- Tune approved MST port costs and priorities based on the intended topology.
Explanation
Correct Answer
B:Align MSTP region name revision and VLAN-to-instance mapping across intended peers. MST region identity depends on matching region attributes including VLAN mapping digest. The expected validation is that switches report the same MST region and shared MSTI topology.
Incorrect Answers
A:Change the BGP local AS to make mismatched MST region digests agree. This is a risky or ineffective shortcut for MSTP region name revision and VLAN digest. Slight configuration mismatches can create independent MST regions and unexpected port states.
C:Configure supported Layer 2 Protocol Tunneling for selected customer control protocols. This addresses L2PT customer BPDU tunneling rather than the required MSTP region name revision and VLAN digest decision. MST region identity depends on matching region attributes including VLAN mapping digest.
D:Tune approved MST port costs and priorities based on the intended topology. This addresses MSTP root port and alternate path rather than the required MSTP region name revision and VLAN digest decision. MST region identity depends on matching region attributes including VLAN mapping digest.
Question 271
A branch bandwidth issue appears because multicast continues hairpinning through a distant RP. Which next investigation or correction is MOST appropriate?
- Disable all unicast routes to the source to force a healthy shortest-path tree.
- Inspect (*,G) and (S,G) state and RPF interface during reception.
- Inspect destination group fields in received packets and routing entries.
- Inspect IGMPv3 (S,G) membership report and associated forwarding state.
Explanation
Correct Answer
B:Inspect (*,G) and (S,G) state and RPF interface during reception. This checks whether a (S,G) shortest-path tree forms when supported and efficient source routing is available.
Incorrect Answers
A:Disable all unicast routes to the source to force a healthy shortest-path tree. That bypass leaves the ASM shared tree versus SPT switchover issue unresolved. Assuming all ASM traffic must stay permanently on RP shared tree may waste bandwidth.
C:Inspect destination group fields in received packets and routing entries. That check applies chiefly to IPv4 multicast group address versus unicast, not the current ASM shared tree versus SPT switchover issue. PIM-SM can transition from shared RP tree to a source shortest-path tree.
D:Inspect IGMPv3 (S,G) membership report and associated forwarding state. That check applies chiefly to IGMPv3 source include mode, not the current ASM shared tree versus SPT switchover issue. PIM-SM can transition from shared RP tree to a source shortest-path tree.
Question 272
A shared service router must reach devices across multiple private VLAN secondary groups. Select TWO statements that correctly combine the Private VLAN community and promiscuous roles implementation, its evidence, or its governing principle.
- Same-community endpoints communicate while different communities stay isolated.
- Set every service port to isolated and claim community members will keep talking.
- Identify MAC learning state and remediate loops or incorrect topology.
- Configure community secondary roles and the appropriate promiscuous uplink association.
- Configure compatible Multiple VLAN Registration Protocol operation on supported links.
Explanation
Correct Answers
A:Same-community endpoints communicate while different communities stay isolated. This is direct observable evidence for Private VLAN community and promiscuous roles.
D:Configure community secondary roles and the appropriate promiscuous uplink association. This is the intended implementation action for Private VLAN community and promiscuous roles.
Incorrect Answers
B:Set every service port to isolated and claim community members will keep talking. This would not be an appropriate Private VLAN community and promiscuous roles decision. Mistaking community roles for isolated roles can interrupt same-group operation.
C:Identify MAC learning state and remediate loops or incorrect topology. This belongs to Ethernet MAC learning and flooding, not the specified Private VLAN community and promiscuous roles operation. Private VLAN community ports have scoped peer reachability and promiscuous ports serve shared resources.
E:Configure compatible Multiple VLAN Registration Protocol operation on supported links. This belongs to MVRP dynamic VLAN registration, not the specified Private VLAN community and promiscuous roles operation. Private VLAN community ports have scoped peer reachability and promiscuous ports serve shared resources.
Question 273
After a route-filter change an unwanted IPv6 summary appears as an OSPFv3 external. Which technical principle BEST explains the OSPFv3 routing policy for external IPv6 decision?
- Routing policy must match the relevant address family as well as eligible source routes.
- OSPF database exchange can stall when peers disagree on interface MTU.
- EVPN all-active multihoming can use parallel forwarding paths with designated loop protection.
- OSPF authentication compatibility is independent of ordinary IP reachability.
Explanation
Correct Answer
A:Routing policy must match the relevant address family as well as eligible source routes. In this situation, the relevant action is to apply a guarded OSPFv3 export policy matching the correct inet6 source and prefix.
Incorrect Answers
B:OSPF database exchange can stall when peers disagree on interface MTU. That principle is related to OSPF interface MTU mismatch, not the main OSPFv3 routing policy for external IPv6 choice. Reusing an IPv4-only route filter can leave IPv6 export expectations unmet.
C: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 OSPFv3 routing policy for external IPv6 choice. Reusing an IPv4-only route filter can leave IPv6 export expectations unmet.
D:OSPF authentication compatibility is independent of ordinary IP reachability. That principle is related to OSPF authentication key or algorithm, not the main OSPFv3 routing policy for external IPv6 choice. Reusing an IPv4-only route filter can leave IPv6 export expectations unmet.
Question 274
A new interconnect permits routing control ICMP but rejects BGP session initiation. Which technical principle BEST explains the BGP TCP 179 and firewall reachability decision?
- Filter terms are evaluated in policy order subject to terminating actions.
- BGP neighbor state and route installation are separate control-plane gates.
- MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
- BGP relies on TCP transport and does not form merely because IP reachability exists.
Explanation
Correct Answer
D:BGP relies on TCP transport and does not form merely because IP reachability exists. In this situation, the relevant action is to permit the intended TCP179 flow under explicit control-plane security policy.
Incorrect Answers
A:Filter terms are evaluated in policy order subject to terminating actions. That principle is related to Filter-based VLAN rule precedence, not the main BGP TCP 179 and firewall reachability choice. Rejecting TCP session establishment keeps BGP Idle or Active.
B:BGP neighbor state and route installation are separate control-plane gates. That principle is related to BGP hidden and rejected path diagnosis, not the main BGP TCP 179 and firewall reachability choice. Rejecting TCP session establishment keeps BGP Idle or Active.
C:MED is a nontransitive path attribute often compared between paths from the same neighboring AS. That principle is related to BGP MED inbound traffic hint, not the main BGP TCP 179 and firewall reachability choice. Rejecting TCP session establishment keeps BGP Idle or Active.
Question 275
An ASM receiver first gets traffic through its RP before moving toward a direct source path. After deploying the recommended ASM shared tree versus SPT switchover change, which result MOST directly verifies success?
- Expected adjacency relationships achieve correct state for the selected network type.
- Every receiver-facing router resolves the same intended RP for each permitted group.
- A (S,G) shortest-path tree forms when supported and efficient source routing is available.
- Periodic queries refresh receiver membership and groups do not unexpectedly expire.
Explanation
Correct Answer
C:A (S,G) shortest-path tree forms when supported and efficient source routing is available. This is the directly observable outcome for ASM shared tree versus SPT switchover. PIM-SM can transition from shared RP tree to a source shortest-path tree.
Incorrect Answers
A:Expected adjacency relationships achieve correct state for the selected network type. This validates OSPF neighbor state troubleshooting workflow but does not directly demonstrate the required ASM shared tree versus SPT switchover result. PIM-SM can transition from shared RP tree to a source shortest-path tree.
B:Every receiver-facing router resolves the same intended RP for each permitted group. This validates Static RP mapping group range but does not directly demonstrate the required ASM shared tree versus SPT switchover result. PIM-SM can transition from shared RP tree to a source shortest-path tree.
D:Periodic queries refresh receiver membership and groups do not unexpectedly expire. This validates IGMP querier on subscriber VLAN but does not directly demonstrate the required ASM shared tree versus SPT switchover result. PIM-SM can transition from shared RP tree to a source shortest-path tree.
Question 276
An EVPN MAC and IP binding does not appear at a remote bridge domain. Which technical principle BEST explains the EVPN Type2 MAC IP advertisement decision?
- EVPN Type2 routes advertise host MAC addresses with optional IP binding.
- ESI identifies a shared multihomed Ethernet segment to EVPN control plane.
- VXLAN network identifiers distinguish overlay Layer 2 broadcast domains.
- Server-recovery behavior and authentication session lifecycle affect effective access.
Explanation
Correct Answer
A:EVPN Type2 routes advertise host MAC addresses with optional IP binding. In this situation, the relevant action is to verify local MAC learning and Type2 MAC/IP route advertisement and import.
Incorrect Answers
B: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 Type2 MAC IP advertisement choice. Missing or stale Type2 routes cause blackholing or misdirected unicast traffic.
C:VXLAN network identifiers distinguish overlay Layer 2 broadcast domains. That principle is related to VXLAN VNI to VLAN association, not the main EVPN Type2 MAC IP advertisement choice. Missing or stale Type2 routes cause blackholing or misdirected unicast traffic.
D:Server-recovery behavior and authentication session lifecycle affect effective access. That principle is related to RADIUS server-fail remediation and reauthentication, not the main EVPN Type2 MAC IP advertisement choice. Missing or stale Type2 routes cause blackholing or misdirected unicast traffic.
Question 277
An enterprise advertises one prefix through two points to the same upstream AS. Which configuration or operational step BEST meets the stated requirement?
- Assign MED through a spanning-tree bridge priority and call it a BGP attribute.
- Match and add or delete only documented communities using supported Junos policy statements.
- Export appropriate MED values where comparison conditions and policy support them.
- Permit the intended TCP179 flow under explicit control-plane security policy.
Explanation
Correct Answer
C:Export appropriate MED values where comparison conditions and policy support them. MED is a nontransitive path attribute often compared between paths from the same neighboring AS. The expected validation is that the upstream accepts advertised MED values with understood decision constraints.
Incorrect Answers
A:Assign MED through a spanning-tree bridge priority and call it a BGP attribute. This is a risky or ineffective shortcut for BGP MED inbound traffic hint. Assuming MED overrides every higher-priority BGP selection criterion leads to false expectations.
B:Match and add or delete only documented communities using supported Junos policy statements. This addresses BGP communities match and deletion rather than the required BGP MED inbound traffic hint decision. MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
D:Permit the intended TCP179 flow under explicit control-plane security policy. This addresses BGP TCP 179 and firewall reachability rather than the required BGP MED inbound traffic hint decision. MED is a nontransitive path attribute often compared between paths from the same neighboring AS.
Question 278
A wiring-closet switch moves all ports into full employee access when RADIUS times out. Which next investigation or correction is MOST appropriate?
- Treat every invalid password as proof RADIUS is down and admit all users.
- Test actual RADIUS outage distinct from deliberate Access-Reject responses.
- Inspect authenticator sessions and RADIUS logs before and after service restoration.
- Verify assigned VLAN and ACLs with valid employee and guest test clients.
Explanation
Correct Answer
B:Test actual RADIUS outage distinct from deliberate Access-Reject responses. This checks whether aAA outages trigger the documented limited continuity state and recovery restores normal authentication.
Incorrect Answers
A:Treat every invalid password as proof RADIUS is down and admit all users. That bypass leaves the RADIUS server unreachable fallback policy issue unresolved. Fail-open all access during AAA outages can expose critical assets.
C:Inspect authenticator sessions and RADIUS logs before and after service restoration. That check applies chiefly to RADIUS server-fail remediation and reauthentication, not the current RADIUS server unreachable fallback policy issue. Server timeout and explicit credential rejection should use different fallback decisions.
D:Verify assigned VLAN and ACLs with valid employee and guest test clients. That check applies chiefly to Guest VLAN for unauthenticated clients, not the current RADIUS server unreachable fallback policy issue. Server timeout and explicit credential rejection should use different fallback decisions.
Question 279
A port carries the PC data untagged but the handset sends voice frames to the wrong tagged VLAN. Which technical principle BEST explains the Voice VLAN tagged versus PC data traffic decision?
- Phone access-port design can carry tagged voice and untagged data for separate policies.
- Authentication monitoring must inspect credentials authorization and port state separately.
- Phone pass-through ports need explicit data security and QoS trust design.
- IEEE PoE total power budget and per-port allocation constrain powered endpoints.
Explanation
Correct Answer
A:Phone access-port design can carry tagged voice and untagged data for separate policies. In this situation, the relevant action is to set correct voice VLAN membership and data VLAN handling for the access port.
Incorrect Answers
B:Authentication monitoring must inspect credentials authorization and port state separately. That principle is related to Junos Layer 2 authentication session monitoring, not the main Voice VLAN tagged versus PC data traffic choice. Treating both streams as one unrestricted VLAN can violate QoS and segmentation rules.
C:Phone pass-through ports need explicit data security and QoS trust design. That principle is related to Phone and PC shared switch-port security, not the main Voice VLAN tagged versus PC data traffic choice. Treating both streams as one unrestricted VLAN can violate QoS and segmentation rules.
D:IEEE PoE total power budget and per-port allocation constrain powered endpoints. That principle is related to PoE power budget switch capacity, not the main Voice VLAN tagged versus PC data traffic choice. Treating both streams as one unrestricted VLAN can violate QoS and segmentation rules.
Question 280
An overly aggressive dampening design suppresses a recovered critical prefix. Which next investigation or correction is MOST appropriate?
- Examine suppression status penalty decay and recovery timing.
- Check BGP advertised families and show route table inet6.0 protocol bgp.
- Inspect reflected path originator ID cluster list and neighbor client roles.
- Raise Ethernet MTU to eliminate every BGP route-flap penalty.
Explanation
Correct Answer
A:Examine suppression status penalty decay and recovery timing. This checks whether flapping prefixes are damped according to intended thresholds and recover within acceptable time.
Incorrect Answers
B:Check BGP advertised families and show route table inet6.0 protocol bgp. That check applies chiefly to BGP NLRI IPv6 unicast inet6 family, not the current BGP route damping flap penalty issue. Route damping suppresses unstable routes but adds recovery latency.
C:Inspect reflected path originator ID cluster list and neighbor client roles. That check applies chiefly to BGP route reflection cluster, not the current BGP route damping flap penalty issue. Route damping suppresses unstable routes but adds recovery latency.
D:Raise Ethernet MTU to eliminate every BGP route-flap penalty. That bypass leaves the BGP route damping flap penalty issue unresolved. Damping critical destinations without review can prolong customer downtime.
