Cisco 350-501 Practice Test 17
Question 160
For an original SPCOR service-provider engineering scenario, consider: A carrier uses OSPFv3 for IPv6 core connectivity but enables the process without activating the intended interfaces and sees no IPv6 prefixes. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding.
- Check: Inspect IPv6 link-local neighbors, interface instance and area data, OSPFv3 LSDB and installed IPv6 routes.
- Assume OSPFv2 neighbor establishment alone causes the same interfaces to participate in OSPFv3 automatically.
- Change: Deploy route reflection with deliberate client and cluster design and preserve IGP reachability to advertised BGP next hops.
- Check: Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
Explanation
Correct Answer
A:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. Evidence: Inspect IPv6 link-local neighbors, interface instance and area data, OSPFv3 LSDB and installed IPv6 routes.
B:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. Inspect IPv6 link-local neighbors, interface instance and area data, OSPFv3 LSDB and installed IPv6 routes.
Incorrect Answers
C:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
D:This option addresses a different service provider engineering topic (iBGP route reflector cluster and next-hop reachability) rather than the documented OSPFv3 IPv6 addressing and adjacencies decision.
E:Check: Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
Question 161
A service provider network engineer is reviewing this backbone or customer-service scenario: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges. A proposed shortcut is: Assume OSPFv2 neighbor establishment alone causes the same interfaces to participate in OSPFv3 automatically. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Assume OSPFv2 neighbor establishment alone causes the same interfaces to participate in OSPFv3 automatically.
- Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation.
- Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding.
Explanation
Correct Answer
D:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges.
Incorrect Answers
A:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. Applied case: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges.
B:This option addresses a different service provider engineering topic (BGP Additional Paths PIC and fast failover) rather than the documented OSPFv3 IPv6 addressing and adjacencies decision.
C:Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
Question 162
A Cisco service provider design review finds: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges. The team proposes: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
- OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
- LACP negotiates compatible members into a logical bundle while per-flow hashing commonly keeps a flow on one member to preserve packet order.
- Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
Explanation
Correct Answer
B:Demonstrable success requires: Stable OSPFv3 adjacencies advertise the intended IPv6 prefixes with reachable next hops.
Incorrect Answers
A:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
C:LACP negotiates compatible members into a logical bundle while per-flow hashing commonly keeps a flow on one member to preserve packet order. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
D:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges.
Question 163
The service provider operations team has not yet approved a change. Current evidence indicates: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Inspect IPv6 link-local neighbors, interface instance and area data, OSPFv3 LSDB and installed IPv6 routes.
- Compare per-protocol neighbor state, error messages, encapsulation, path reachability, authentication and interface counters.
- Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
Explanation
Correct Answer
B:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. This check tests the actual routing, transport or service boundary before an operationally risky response.
Incorrect Answers
A:Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
C:Compare per-protocol neighbor state, error messages, encapsulation, path reachability, authentication and interface counters. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
D:Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram. Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges.
Question 164
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges. 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.
- Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets.
- Stable OSPFv3 adjacencies advertise the intended IPv6 prefixes with reachable next hops.
- Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches.
- Only planned prefixes cross the protocol boundary once and core convergence remains stable under service-route churn.
Explanation
Correct Answer
B:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. The approved implementation step was: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding.
Incorrect Answers
A:Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets. Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges.
C:This option addresses a different service provider engineering topic (OSPFv2 neighbor state and MTU mismatch) rather than the documented OSPFv3 IPv6 addressing and adjacencies decision.
D:Only planned prefixes cross the protocol boundary once and core convergence remains stable under service-route churn. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
Question 165
An implementation sign-off request identifies the following problem: Two routers exchange IPv6 link-local hellos but a required OSPFv3 area or instance setting differs and the neighbor never fully converges. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding. Verify: Inspect IPv6 link-local neighbors, interface instance and area data, OSPFv3 LSDB and installed IPv6 routes.
- Change: Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls. Verify: Compare per-protocol neighbor state, error messages, encapsulation, path reachability, authentication and interface counters.
- Change: Verify aggregation protocol, member compatibility, hashing expectations and actual active bandwidth before designing redundancy or QoS. Verify: Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows.
- Change: Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas. Verify: Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
Explanation
Correct Answer
A:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. The change is successful only when: Stable OSPFv3 adjacencies advertise the intended IPv6 prefixes with reachable next hops.
Incorrect Answers
B:Change: Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls.
C:Change: Verify aggregation protocol, member compatibility, hashing expectations and actual active bandwidth before designing redundancy or QoS.
D:Change: Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas. OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
Question 166
A service provider network engineer is reviewing this backbone or customer-service scenario: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes. A proposed shortcut is: Advertise a blanket aggregate for unrelated prefixes and expect all OSPF external LSAs to enter every stub area. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation.
- Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
- Advertise a blanket aggregate for unrelated prefixes and expect all OSPF external LSAs to enter every stub area.
- Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data.
Explanation
Correct Answer
A:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes.
Incorrect Answers
B:This option addresses a different service provider engineering topic (IOS XR route policy language and Cisco route maps) rather than the documented OSPF multiarea ABR area types and route summarization decision.
C:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
D:Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Question 167
A Cisco service provider design review finds: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes. The team proposes: Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- IS-IS NET encodes an area and unique system identifier; Level-1 flooding is area scoped while Level-2 connects interarea backbone reachability.
- Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
- IS-IS adjacencies use link-local protocol hellos and compatible level, circuit and network settings; IP reachability alone does not create a neighbor.
- OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Explanation
Correct Answer
D:Demonstrable success requires: Stub or normal areas receive only intended advertisements and no unreachable discontiguous summary is treated as valid service connectivity. Applied case: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes.
Incorrect Answers
A:IS-IS NET encodes an area and unique system identifier; Level-1 flooding is area scoped while Level-2 connects interarea backbone reachability. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
B:This option addresses a different service provider engineering topic (Graceful restart NSR and maintenance continuity) rather than the documented OSPF multiarea ABR area types and route summarization decision.
C:IS-IS adjacencies use link-local protocol hellos and compatible level, circuit and network settings; IP reachability alone does not create a neighbor. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Question 168
The service provider operations team has not yet approved a change. Current evidence indicates: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie.
- Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
- Check route-reflector client relationships, originator and cluster attributes, BGP next-hop resolution and the RIB versus FIB.
- Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses.
Explanation
Correct Answer
D:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. Applied case: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes.
Incorrect Answers
A:Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
B:Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
C:Check route-reflector client relationships, originator and cluster attributes, BGP next-hop resolution and the RIB versus FIB. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Question 169
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes. 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.
- Stub or normal areas receive only intended advertisements and no unreachable discontiguous summary is treated as valid service connectivity.
- Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries.
- The preferred transit path wins for documented policy reasons without unexpected route filtering or next-hop failure.
- Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling.
Explanation
Correct Answer
A:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. The result must be validated using the documented device, service or access context.
Incorrect Answers
B:Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
C:The preferred transit path wins for documented policy reasons without unexpected route filtering or next-hop failure. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
D:Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Question 170
For an original SPCOR service-provider engineering scenario, consider: A provider configures a stub area but expects external LSAs to be flooded into it unchanged, then investigates missing type-5 routes. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation.
- Advertise a blanket aggregate for unrelated prefixes and expect all OSPF external LSAs to enter every stub area.
- Check: Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses.
- Change: Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link.
- Check: Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
Explanation
Correct Answer
A:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. Acceptance: Stub or normal areas receive only intended advertisements and no unreachable discontiguous summary is treated as valid service connectivity.
C:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. Required intervention: Choose correct OSPF area behavior and summarization boundaries, confirming permitted external and interarea route propagation.
Incorrect Answers
B:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
D:Change: Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
E:Check: Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram. OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
