Cisco 350-501 Practice Test 57
Question 560
For an original SPCOR service-provider engineering scenario, consider: A customer VRF needs controlled access to a shared DNS service but the operator exports all customer routes into every other customer VRF. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
- Import every customer VRF route into every other VRF as the only way to offer a single shared DNS service.
- Change: Match multicast routing mode and receiver source selection, then verify PIM RPF and RP or source-tree behavior for the chosen model.
- Check: Compare imported RT lists, VRF next hops, shared service return routing and firewall policy using two customer tenants.
- Check: Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs.
Explanation
Correct Answer
A:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. Acceptance: Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted.
D:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. Required intervention: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
Incorrect Answers
B:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
C:Change: Match multicast routing mode and receiver source selection, then verify PIM RPF and RP or source-tree behavior for the chosen model. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
E:Check: Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
Question 561
A service provider network engineer is reviewing this backbone or customer-service scenario: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point. A proposed shortcut is: Import every customer VRF route into every other VRF as the only way to offer a single shared DNS service. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Match the Ethernet service type to required point-to-point, multipoint or rooted traffic relationships and enforce the appropriate endpoint split rules.
- Advertise and import the proper EVPN MAC or IP reachability route type and associated route targets for the requested L2 or L3 service.
- Import every customer VRF route into every other VRF as the only way to offer a single shared DNS service.
- Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
Explanation
Correct Answer
D:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point.
Incorrect Answers
A:Match the Ethernet service type to required point-to-point, multipoint or rooted traffic relationships and enforce the appropriate endpoint split rules. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
B:This option addresses a different service provider engineering topic (EVPN MAC IP route types and L2 reachability) rather than the documented L3VPN extranet shared service and internet breakout decision.
C:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. Applied case: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point.
Question 562
A Cisco service provider design review finds: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point. The team proposes: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- G.8032 Ethernet Ring Protection controls blocked and active ring links, while Ethernet OAM provides fault detection and service continuity evidence.
- L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
- EVC tag operations such as push pop and translation are contextual to a service instance and may require symmetric rewrite at both attachment points.
- PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
Explanation
Correct Answer
B:Demonstrable success requires: Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted. Applied case: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point.
Incorrect Answers
A:G.8032 Ethernet Ring Protection controls blocked and active ring links, while Ethernet OAM provides fault detection and service continuity evidence. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
C:EVC tag operations such as push pop and translation are contextual to a service instance and may require symmetric rewrite at both attachment points. Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point.
D:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
Question 563
The service provider operations team has not yet approved a change. Current evidence indicates: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Inspect ring protection state, OAM continuity-check results, link-failure events and convergence on one forced-ring break.
- Compare imported RT lists, VRF next hops, shared service return routing and firewall policy using two customer tenants.
- Map UNI endpoints and approved source-destination pairs, then test leaf-to-leaf and root-to-leaf reachability in the staged EVC.
- Check class-map matches, DSCP or MPLS TC, policer violations, shaping queue depth, WRED counters and customer throughput during controlled congestion.
Explanation
Correct Answer
B:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. Confirm afterward that: Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted.
Incorrect Answers
A:Inspect ring protection state, OAM continuity-check results, link-failure events and convergence on one forced-ring break. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
C:Map UNI endpoints and approved source-destination pairs, then test leaf-to-leaf and root-to-leaf reachability in the staged EVC. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
D:Check class-map matches, DSCP or MPLS TC, policer violations, shaping queue depth, WRED counters and customer throughput during controlled congestion. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
Question 564
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- High-priority services meet policy while excess traffic is bounded and ordinary customer classes retain their contracted forwarding share.
- Only authorized customer VPNs extend between providers and payload forwarding follows a valid label-switched or agreed interconnect path.
- Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted.
- The customer carrier preserves its own service topology while the backbone transports authorized labeled traffic without core route explosion.
Explanation
Correct Answer
C:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. The approved implementation step was: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
Incorrect Answers
A:High-priority services meet policy while excess traffic is bounded and ordinary customer classes retain their contracted forwarding share. Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point.
B:Only authorized customer VPNs extend between providers and payload forwarding follows a valid label-switched or agreed interconnect path. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
D:The customer carrier preserves its own service topology while the backbone transports authorized labeled traffic without core route explosion. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
Question 565
An implementation sign-off request identifies the following problem: Several remote VPN sites require centralized internet access while their default routes accidentally bypass the intended security inspection point. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Use matching IGMP or MLD listener protocols and supported source-filtering behavior on the appropriate IPv4 or IPv6 access segment. Verify: Inspect IGMPv3 source lists or MLD reports, snooping table, receiver membership and forwarded multicast stream source identities.
- Change: Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths. Verify: Compare imported RT lists, VRF next hops, shared service return routing and firewall policy using two customer tenants.
- Change: Build the supported carrier-supporting-carrier transport and routing boundary, retaining customer-carrier control where intended and validating labeled reachability. Verify: Check labeled route handoff, VRF or transport separation, next-hop reachability and a representative downstream customer LSP.
- Change: Match the Ethernet service type to required point-to-point, multipoint or rooted traffic relationships and enforce the appropriate endpoint split rules. Verify: Map UNI endpoints and approved source-destination pairs, then test leaf-to-leaf and root-to-leaf reachability in the staged EVC.
Explanation
Correct Answer
B:L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility. The change is successful only when: Customers reach only approved shared services and internet egress while peer-to-peer tenant access remains restricted.
Incorrect Answers
A:This option addresses a different service provider engineering topic (IGMPv3 MLD and multicast membership scope) rather than the documented L3VPN extranet shared service and internet breakout decision.
C:Change: Build the supported carrier-supporting-carrier transport and routing boundary, retaining customer-carrier control where intended and validating labeled reachability. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
D:Change: Match the Ethernet service type to required point-to-point, multipoint or rooted traffic relationships and enforce the appropriate endpoint split rules. L3VPN extranet services require controlled cross-VRF routing and return reachability; sharing a few service routes need not grant full tenant-to-tenant visibility.
Question 566
A service provider network engineer is reviewing this backbone or customer-service scenario: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router. A proposed shortcut is: Configure an RP-dependent workflow for SSM and assume group-only subscriptions identify any required source automatically. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Configure an RP-dependent workflow for SSM and assume group-only subscriptions identify any required source automatically.
- Match multicast routing mode and receiver source selection, then verify PIM RPF and RP or source-tree behavior for the chosen model.
- Configure consistent service and customer VLAN tag handling with explicit encapsulation and correct cross-PE mapping.
- Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths.
Explanation
Correct Answer
B:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router.
Incorrect Answers
A:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
C:Configure consistent service and customer VLAN tag handling with explicit encapsulation and correct cross-PE mapping. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
D:Build selective route leaking or shared-service VRF connectivity with scoped route targets and explicit security controls for shared and internet paths. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
Question 567
A Cisco service provider design review finds: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router. The team proposes: Match multicast routing mode and receiver source selection, then verify PIM RPF and RP or source-tree behavior for the chosen model. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Carrier supporting carrier lets a provider transport another carrier's VPN or MPLS reachability without needing full visibility into every downstream end-customer route.
- EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions.
- PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
- Policing can drop or remark out-of-profile traffic, shaping buffers and paces egress, and weighted congestion avoidance can reduce tail-drop pressure under load.
Explanation
Correct Answer
C:Demonstrable success requires: Intended subscribers receive the selected source and nonmembers do not trigger unwanted flood or RP dependence. Applied case: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router.
Incorrect Answers
A:This option addresses a different service provider engineering topic (Carrier supporting carrier hierarchical VPN transport) rather than the documented PIM sparse-mode SSM and rendezvous-point behavior decision.
B:EVPN uses MP-BGP to signal Ethernet MAC or IP reachability and other service state; type-2 and type-5 serve different reachability functions. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
D:Policing can drop or remark out-of-profile traffic, shaping buffers and paces egress, and weighted congestion avoidance can reduce tail-drop pressure under load. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
Question 568
The service provider operations team has not yet approved a change. Current evidence indicates: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Inspect (*,G) and (S,G) state, RP mapping, RPF interface and actual receiver joins under a test stream.
- Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs.
- Check EVPN address-family advertisements, route types, Ethernet segment and EVI context, route targets and remote forwarding database.
- Compare ESI advertisements, DF election, MAC mobility sequence and traffic behavior before and after one PE uplink failure.
Explanation
Correct Answer
A:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. Applied case: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router.
Incorrect Answers
B:Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
C:Check EVPN address-family advertisements, route types, Ethernet segment and EVI context, route targets and remote forwarding database. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
D:Compare ESI advertisements, DF election, MAC mobility sequence and traffic behavior before and after one PE uplink failure. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
Question 569
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- Customer devices receive frames in the specified tagging format and service VLANs remain separated despite provider translations.
- Permitted locations communicate according to the contracted Ethernet service while disallowed leaf or tenant pairs remain isolated.
- The dual-homed customer retains connectivity with correct single-copy flooding and no persistent Layer-2 forwarding loops.
- Intended subscribers receive the selected source and nonmembers do not trigger unwanted flood or RP dependence.
Explanation
Correct Answer
D:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. The result must be validated using the documented device, service or access context.
Incorrect Answers
A:Customer devices receive frames in the specified tagging format and service VLANs remain separated despite provider translations. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
B:Permitted locations communicate according to the contracted Ethernet service while disallowed leaf or tenant pairs remain isolated. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
C:The dual-homed customer retains connectivity with correct single-copy flooding and no persistent Layer-2 forwarding loops. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
Question 570
For an original SPCOR service-provider engineering scenario, consider: A multicast source sends to a sparse-mode group but receivers receive no packets because the designated RP address is unreachable from the first-hop router. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Configure an RP-dependent workflow for SSM and assume group-only subscriptions identify any required source automatically.
- Check: Inspect (*,G) and (S,G) state, RP mapping, RPF interface and actual receiver joins under a test stream.
- Change: Use matching IGMP or MLD listener protocols and supported source-filtering behavior on the appropriate IPv4 or IPv6 access segment.
- Change: Match multicast routing mode and receiver source selection, then verify PIM RPF and RP or source-tree behavior for the chosen model.
- Check: Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs.
Explanation
Correct Answer
B:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. Acceptance: Intended subscribers receive the selected source and nonmembers do not trigger unwanted flood or RP dependence.
D:PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery. Evidence: Inspect (*,G) and (S,G) state, RP mapping, RPF interface and actual receiver joins under a test stream.
Incorrect Answers
A:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
C:Change: Use matching IGMP or MLD listener protocols and supported source-filtering behavior on the appropriate IPv4 or IPv6 access segment. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
E:Check: Inspect customer PIM state, mVPN BGP or tree signaling, receiver joins, replication counters and stream reachability between PEs. PIM-SM may use a rendezvous point for shared-tree discovery, while SSM uses explicit source-group state and normally avoids RP discovery.
