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Exam Code: JN0-664

Exam Name: Service Provider Routing and Switching, Professional (JNCIP-SP)

Certification Provider: Juniper

Corresponding Certification: JNCIP-SP

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"Service Provider Routing and Switching, Professional (JNCIP-SP) Exam", also known as JN0-664 exam, is a Juniper certification exam.

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Juniper JN0-664 Practice Test 80

Question 790

An EVPN multihoming service uses per-ES designated forwarding behavior. Observed: A newly connected PE advertises the service but never forwards BUM frames when elected. What evidence would validate recovery from this precise failure mode?

  1. Each intended site imports the circuit NLRI and builds its matching connection.
  2. Each VLAN has the expected DF and BUM traffic follows one permitted path.
  3. Only the elected forwarding path replicates BUM traffic and failover stays loss-limited.
  4. Every customer VPLS or circuit includes only its authorized sites.

Explanation

Correct Answer

B:

The intended result is Each VLAN has the expected DF and BUM traffic follows one permitted path. It specifically verifies recovery from the pe's df election view disagrees because vlan or ethernet tag association is inconsistent, which produced the original symptom: A newly connected PE advertises the service but never forwards BUM frames when elected. It is stronger evidence than a generic interface-up indicator.

Incorrect Answers

A:

This result is useful in another case with evidence One remote PE receives BGP routes but does not establish the required connection. It does not test recovery from a newly connected pe advertises the service but never forwards bum frames when elected. Check instead whether each VLAN has the expected DF and BUM traffic follows one permitted path.

C:

It confirms an unrelated service correction: Ethernet segment split-horizon or designated-forwarder behavior is incorrect. The present case reports A newly connected PE advertises the service but never forwards BUM frames when elected. Its completion test is Each VLAN has the expected DF and BUM traffic follows one permitted path.

D:

That observation would verify a separate fault involving l2vpn rt filters permit cross-service membership despite separate service definitions. Its symptom is A transit PE imports endpoints from an unrelated L2VPN. For this case the actual issue is the pe's df election view disagrees because vlan or ethernet tag association is inconsistent, and the relevant success signal is Each VLAN has the expected DF and BUM traffic follows one permitted path.

Question 791

An EVPN multihoming service uses per-ES designated forwarding behavior. Observed: A newly connected PE advertises the service but never forwards BUM frames when elected. What underlying protocol or service configuration problem best explains the evidence?

  1. L2VPN RT filters permit cross-service membership despite separate service definitions.
  2. Import route targets do not include the originating L2VPN service.
  3. Ethernet segment split-horizon or designated-forwarder behavior is incorrect.
  4. The PE's DF election view disagrees because VLAN or Ethernet tag association is inconsistent.

Explanation

Correct Answer

D:

Because a newly connected PE advertises the service but never forwards BUM frames when elected, the likely cause is the pe's df election view disagrees because vlan or ethernet tag association is inconsistent. It is testable: Align Ethernet tag/service association across multihomed PEs and verify DF election inputs. Expected follow-up: Each VLAN has the expected DF and BUM traffic follows one permitted path.

Incorrect Answers

A:

The stated cause is possible elsewhere but explains a transit pe imports endpoints from an unrelated l2vpn, not a newly connected pe advertises the service but never forwards bum frames when elected. This incident is better attributed to the pe's df election view disagrees because vlan or ethernet tag association is inconsistent.

B:

That explanation fits another condition: One remote PE receives BGP routes but does not establish the required connection. The evidence here is A newly connected PE advertises the service but never forwards BUM frames when elected. Its closer root cause is The PE's DF election view disagrees because VLAN or Ethernet tag association is inconsistent.

C:

Ethernet segment split-horizon or designated-forwarder behavior is incorrect. would normally be accompanied by a customer-facing ce sees duplicate broadcast frames after a pe failure. The observed symptom is different: A newly connected PE advertises the service but never forwards BUM frames when elected. The likely cause is The PE's DF election view disagrees because VLAN or Ethernet tag association is inconsistent.

Question 792

An EVPN multihoming service uses per-ES designated forwarding behavior. Observed: A newly connected PE advertises the service but never forwards BUM frames when elected. Which ongoing validation gate would best detect a recurrence of this problem?

  1. For each approved related change, verify that each VLAN has the expected DF and BUM traffic follows one permitted path. Flag recurrence if a newly connected PE advertises the service but never forwards BUM frames when elected.
  2. For each approved related change, verify that only the elected forwarding path replicates BUM traffic and failover stays loss-limited. Flag recurrence if a customer-facing CE sees duplicate broadcast frames after a PE failure.
  3. For each approved related change, verify that each intended site imports the circuit NLRI and builds its matching connection. Flag recurrence if one remote PE receives BGP routes but does not establish the required connection.
  4. For each approved related change, verify that every customer VPLS or circuit includes only its authorized sites. Flag recurrence if a transit PE imports endpoints from an unrelated L2VPN.

Explanation

Correct Answer

A:

A useful regression gate tests whether each VLAN has the expected DF and BUM traffic follows one permitted path and alerts when a newly connected PE advertises the service but never forwards BUM frames when elected. This directly checks the technical weakness: The PE's DF election view disagrees because VLAN or Ethernet tag association is inconsistent. The gate is derived from the fictional incident and is not an independent Juniper engineer signoff.

Incorrect Answers

B:

This gate monitors a different failure, a customer-facing ce sees duplicate broadcast frames after a pe failure. It would not detect the current problem: A newly connected PE advertises the service but never forwards BUM frames when elected. The appropriate check requires each VLAN has the expected DF and BUM traffic follows one permitted path.

C:

It is valid for another service scenario but checks one remote pe receives bgp routes but does not establish the required connection. This case instead needs a gate for a newly connected pe advertises the service but never forwards bum frames when elected and evidence that each VLAN has the expected DF and BUM traffic follows one permitted path.

D:

The proposed control is tied to l2vpn rt filters permit cross-service membership despite separate service definitions, typically observed when a transit PE imports endpoints from an unrelated L2VPN. Here the target is the pe's df election view disagrees because vlan or ethernet tag association is inconsistent; monitor each VLAN has the expected DF and BUM traffic follows one permitted path.

Question 793

A BGP L2VPN uses identical customer VLAN identifiers in two separate services. Observed: A transit PE imports endpoints from an unrelated L2VPN. Which change most directly corrects the failure while respecting the existing service boundary?

  1. Assign unique service site IDs and verify remote mapping calculations.
  2. Assign isolated RT import/export sets and check per-service forwarding instance.
  3. Assign the matching planned ESI and compatible ES import/community settings.
  4. Apply the supported active/standby VPLS multihoming policy and test controlled switchover.

Explanation

Correct Answer

B:

The observed condition is A transit PE imports endpoints from an unrelated L2VPN. That indicates l2vpn rt filters permit cross-service membership despite separate service definitions. Applying the proposed remedy directly changes that condition. A concrete completion check is: Every customer VPLS or circuit includes only its authorized sites.

Incorrect Answers

A:

This change belongs to a different Layer 2 VPNs issue: Two attachments map to the same site ID and service endpoints conflict. That issue involves site-id uniqueness is not maintained across the pseudowire service. The current symptom is A transit PE imports endpoints from an unrelated L2VPN. It instead requires assign isolated RT import/export sets and check per-service forwarding instance.

C:

The option may be useful when each PE advertises a different ESI for the same physical Ethernet segment, but that is not the current evidence. Here, a transit PE imports endpoints from an unrelated L2VPN, indicating l2vpn rt filters permit cross-service membership despite separate service definitions. The targeted action is Assign isolated RT import/export sets and check per-service forwarding instance.

D:

This remediates multihoming preference and standby pseudowire behavior were not reconciled, normally indicated by Service recovers briefly then oscillates when the second pseudowire activates. It would leave the observed problem (A transit PE imports endpoints from an unrelated L2VPN) unresolved. Address it with assign isolated RT import/export sets and check per-service forwarding instance.

Question 794

A BGP L2VPN uses identical customer VLAN identifiers in two separate services. Observed: A transit PE imports endpoints from an unrelated L2VPN. After the correction, which result would most convincingly show that this fault is resolved?

  1. The remote EVPN domain recognizes one common segment and converges on failover.
  2. The L2VPN forwarding map contains one consistent circuit per intended site.
  3. Every customer VPLS or circuit includes only its authorized sites.
  4. One active attachment forwards at a time and backup takeover is stable.

Explanation

Correct Answer

C:

After assign isolated RT import/export sets and check per-service forwarding instance, inspect whether every customer VPLS or circuit includes only its authorized sites. This closes the loop between the reported observation (A transit PE imports endpoints from an unrelated L2VPN) and the underlying issue (L2VPN RT filters permit cross-service membership despite separate service definitions).

Incorrect Answers

A:

That observation would verify a separate fault involving ethernet segment identifier mismatch prevents correct multihoming coordination. Its symptom is Each PE advertises a different ESI for the same physical Ethernet segment. For this case the actual issue is l2vpn rt filters permit cross-service membership despite separate service definitions, and the relevant success signal is Every customer VPLS or circuit includes only its authorized sites.

B:

It confirms an unrelated service correction: Site-ID uniqueness is not maintained across the pseudowire service. The present case reports A transit PE imports endpoints from an unrelated L2VPN. Its completion test is Every customer VPLS or circuit includes only its authorized sites.

D:

This result is useful in another case with evidence Service recovers briefly then oscillates when the second pseudowire activates. It does not test recovery from a transit pe imports endpoints from an unrelated l2vpn. Check instead whether every customer VPLS or circuit includes only its authorized sites.

Question 795

A BGP L2VPN uses identical customer VLAN identifiers in two separate services. Observed: A transit PE imports endpoints from an unrelated L2VPN. Which root cause is most consistent with this symptom?

  1. Site-ID uniqueness is not maintained across the pseudowire service.
  2. Multihoming preference and standby pseudowire behavior were not reconciled.
  3. L2VPN RT filters permit cross-service membership despite separate service definitions.
  4. Ethernet segment identifier mismatch prevents correct multihoming coordination.

Explanation

Correct Answer

C:

The reported evidence—A transit PE imports endpoints from an unrelated L2VPN—supports l2vpn rt filters permit cross-service membership despite separate service definitions. The appropriate intervention is to assign isolated RT import/export sets and check per-service forwarding instance, with confirmation from every customer VPLS or circuit includes only its authorized sites. Other causes require actual device-state verification.

Incorrect Answers

A:

Site-ID uniqueness is not maintained across the pseudowire service. would normally be accompanied by two attachments map to the same site id and service endpoints conflict. The observed symptom is different: A transit PE imports endpoints from an unrelated L2VPN. The likely cause is L2VPN RT filters permit cross-service membership despite separate service definitions.

B:

That explanation fits another condition: Service recovers briefly then oscillates when the second pseudowire activates. The evidence here is A transit PE imports endpoints from an unrelated L2VPN. Its closer root cause is L2VPN RT filters permit cross-service membership despite separate service definitions.

D:

The stated cause is possible elsewhere but explains each pe advertises a different esi for the same physical ethernet segment, not a transit pe imports endpoints from an unrelated l2vpn. This incident is better attributed to l2vpn rt filters permit cross-service membership despite separate service definitions.

Question 796

A BGP L2VPN uses identical customer VLAN identifiers in two separate services. Observed: A transit PE imports endpoints from an unrelated L2VPN. Which change-acceptance control is most relevant to preventing this exact failure?

  1. For each approved related change, verify that the remote EVPN domain recognizes one common segment and converges on failover. Flag recurrence if each PE advertises a different ESI for the same physical Ethernet segment.
  2. For each approved related change, verify that the L2VPN forwarding map contains one consistent circuit per intended site. Flag recurrence if two attachments map to the same site ID and service endpoints conflict.
  3. For each approved related change, verify that one active attachment forwards at a time and backup takeover is stable. Flag recurrence if service recovers briefly then oscillates when the second pseudowire activates.
  4. For each approved related change, verify that every customer VPLS or circuit includes only its authorized sites. Flag recurrence if a transit PE imports endpoints from an unrelated L2VPN.

Explanation

Correct Answer

D:

The control is specific to the initial failure. It requires the result Every customer VPLS or circuit includes only its authorized sites. and treats A transit PE imports endpoints from an unrelated L2VPN. as a failure signal. The causal concern is l2vpn rt filters permit cross-service membership despite separate service definitions.

Incorrect Answers

A:

The proposed control is tied to ethernet segment identifier mismatch prevents correct multihoming coordination, typically observed when each PE advertises a different ESI for the same physical Ethernet segment. Here the target is l2vpn rt filters permit cross-service membership despite separate service definitions; monitor every customer VPLS or circuit includes only its authorized sites.

B:

This gate monitors a different failure, two attachments map to the same site id and service endpoints conflict. It would not detect the current problem: A transit PE imports endpoints from an unrelated L2VPN. The appropriate check requires every customer VPLS or circuit includes only its authorized sites.

C:

It is valid for another service scenario but checks service recovers briefly then oscillates when the second pseudowire activates. This case instead needs a gate for a transit pe imports endpoints from an unrelated l2vpn and evidence that every customer VPLS or circuit includes only its authorized sites.

Question 797

A provider restores a dual-homed VPLS attachment after maintenance. Observed: Service recovers briefly then oscillates when the second pseudowire activates. What should the routing engineer change first to address this particular symptom?

  1. Restore proper EVPN Type-3 import and replication next-hop resolution.
  2. Apply the supported active/standby VPLS multihoming policy and test controlled switchover.
  3. Enable compatible MP-BGP L2VPN family and reflection policy.
  4. Configure the contracted matching VC ID and compatible circuit signaling on both endpoints.

Explanation

Correct Answer

B:

The decisive evidence is that Service recovers briefly then oscillates when the second pseudowire activates. This follows from multihoming preference and standby pseudowire behavior were not reconciled. The focused remedy is to apply the supported active/standby VPLS multihoming policy and test controlled switchover. Confirm improvement when one active attachment forwards at a time and backup takeover is stable. Validate on an approved lab or change window before touching production.

Incorrect Answers

A:

This remediates the receiving pe lacks an eligible ingress-replication membership or tunnel mapping, normally indicated by Broadcast and unknown-unicast traffic never reaches one remote PE. It would leave the observed problem (Service recovers briefly then oscillates when the second pseudowire activates) unresolved. Address it with apply the supported active/standby VPLS multihoming policy and test controlled switchover.

C:

The option may be useful when a new spoke receives no Layer 2 VPN membership information, but that is not the current evidence. Here, service recovers briefly then oscillates when the second pseudowire activates, indicating multihoming preference and standby pseudowire behavior were not reconciled. The targeted action is Apply the supported active/standby VPLS multihoming policy and test controlled switchover.

D:

This change belongs to a different Layer 2 VPNs issue: One endpoint reports a matching neighbor but pseudowire status stays Down. That issue involves the local and remote virtual circuit identifiers do not match. The current symptom is Service recovers briefly then oscillates when the second pseudowire activates. It instead requires apply the supported active/standby VPLS multihoming policy and test controlled switchover.

Question 798

A provider restores a dual-homed VPLS attachment after maintenance. Observed: Service recovers briefly then oscillates when the second pseudowire activates. Which acceptance observation best confirms that the proposed change worked?

  1. BUM traffic reaches each subscribed PE exactly as permitted.
  2. Authorized L2VPN NLRI reaches the spoke with intact RD and RT information.
  3. The L2 circuit becomes Up and customer frames traverse the pseudowire.
  4. One active attachment forwards at a time and backup takeover is stable.

Explanation

Correct Answer

D:

This acceptance criterion tests the actual fault. The source evidence was Service recovers briefly then oscillates when the second pseudowire activates. The correction addresses multihoming preference and standby pseudowire behavior were not reconciled; success requires one active attachment forwards at a time and backup takeover is stable.

Incorrect Answers

A:

This result is useful in another case with evidence Broadcast and unknown-unicast traffic never reaches one remote PE. It does not test recovery from service recovers briefly then oscillates when the second pseudowire activates. Check instead whether one active attachment forwards at a time and backup takeover is stable.

B:

That observation would verify a separate fault involving the reflector does not negotiate the l2vpn address family for that client. Its symptom is A new spoke receives no Layer 2 VPN membership information. For this case the actual issue is multihoming preference and standby pseudowire behavior were not reconciled, and the relevant success signal is One active attachment forwards at a time and backup takeover is stable.

C:

It confirms an unrelated service correction: The local and remote virtual circuit identifiers do not match. The present case reports Service recovers briefly then oscillates when the second pseudowire activates. Its completion test is One active attachment forwards at a time and backup takeover is stable.

Question 799

A provider restores a dual-homed VPLS attachment after maintenance. Observed: Service recovers briefly then oscillates when the second pseudowire activates. What is the most likely source of the observed routing or service failure?

  1. The local and remote virtual circuit identifiers do not match.
  2. The reflector does not negotiate the L2VPN address family for that client.
  3. Multihoming preference and standby pseudowire behavior were not reconciled.
  4. The receiving PE lacks an eligible ingress-replication membership or tunnel mapping.

Explanation

Correct Answer

C:

This explanation is the closest match to the observed symptom: Service recovers briefly then oscillates when the second pseudowire activates. The specified root issue is Multihoming preference and standby pseudowire behavior were not reconciled. Repair it through apply the supported active/standby VPLS multihoming policy and test controlled switchover, then check one active attachment forwards at a time and backup takeover is stable.

Incorrect Answers

A:

The local and remote virtual circuit identifiers do not match. would normally be accompanied by one endpoint reports a matching neighbor but pseudowire status stays down. The observed symptom is different: Service recovers briefly then oscillates when the second pseudowire activates. The likely cause is Multihoming preference and standby pseudowire behavior were not reconciled.

B:

The stated cause is possible elsewhere but explains a new spoke receives no layer 2 vpn membership information, not service recovers briefly then oscillates when the second pseudowire activates. This incident is better attributed to multihoming preference and standby pseudowire behavior were not reconciled.

D:

That explanation fits another condition: Broadcast and unknown-unicast traffic never reaches one remote PE. The evidence here is Service recovers briefly then oscillates when the second pseudowire activates. Its closer root cause is Multihoming preference and standby pseudowire behavior were not reconciled.

Question 800

A provider restores a dual-homed VPLS attachment after maintenance. Observed: Service recovers briefly then oscillates when the second pseudowire activates. What operational check best guards against this problem returning?

  1. For each approved related change, verify that one active attachment forwards at a time and backup takeover is stable. Flag recurrence if service recovers briefly then oscillates when the second pseudowire activates.
  2. For each approved related change, verify that authorized L2VPN NLRI reaches the spoke with intact RD and RT information. Flag recurrence if a new spoke receives no Layer 2 VPN membership information.
  3. For each approved related change, verify that the L2 circuit becomes Up and customer frames traverse the pseudowire. Flag recurrence if one endpoint reports a matching neighbor but pseudowire status stays Down.
  4. For each approved related change, verify that bUM traffic reaches each subscribed PE exactly as permitted. Flag recurrence if broadcast and unknown-unicast traffic never reaches one remote PE.

Explanation

Correct Answer

A:

This control asks for the same recovery evidence (One active attachment forwards at a time and backup takeover is stable) and flags recurrence of the same failure (Service recovers briefly then oscillates when the second pseudowire activates). It targets the underlying issue, multihoming preference and standby pseudowire behavior were not reconciled, rather than a different service problem. The exact cadence must be agreed with operations.

Incorrect Answers

B:

The proposed control is tied to the reflector does not negotiate the l2vpn address family for that client, typically observed when a new spoke receives no Layer 2 VPN membership information. Here the target is multihoming preference and standby pseudowire behavior were not reconciled; monitor one active attachment forwards at a time and backup takeover is stable.

C:

This gate monitors a different failure, one endpoint reports a matching neighbor but pseudowire status stays down. It would not detect the current problem: Service recovers briefly then oscillates when the second pseudowire activates. The appropriate check requires one active attachment forwards at a time and backup takeover is stable.

D:

It is valid for another service scenario but checks broadcast and unknown-unicast traffic never reaches one remote pe. This case instead needs a gate for service recovers briefly then oscillates when the second pseudowire activates and evidence that one active attachment forwards at a time and backup takeover is stable.

Service Provider Routing and Switching, Professional (JNCIP-SP) (JN0-664) Practice Tests