Cisco 350-501 Practice Test 15
Question 140
For an original SPCOR service-provider engineering scenario, consider: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Check: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Check: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
- Change local interface description text and assume IS-IS SPF automatically reweights paths according to bandwidth labels.
- Change: Align peer AS, transport source, addressing, family activation and supported eBGP hop reachability for the actual topology.
Explanation
Correct Answer
B:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. Evidence: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
C:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. Acceptance: Preferred paths align with declared metrics while all participating routers interpret the advertised costs consistently.
Incorrect Answers
A:Check: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
D:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
E:Change: Align peer AS, transport source, addressing, family activation and supported eBGP hop reachability for the actual topology. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 141
A service provider network engineer is reviewing this backbone or customer-service scenario: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions. A proposed shortcut is: Change local interface description text and assume IS-IS SPF automatically reweights paths according to bandwidth labels. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding.
- Change local interface description text and assume IS-IS SPF automatically reweights paths according to bandwidth labels.
- Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Choose the appropriate IPv6 transition and address-sharing model for subscriber connectivity, and test mapping state and application behavior end to end.
Explanation
Correct Answer
C:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions.
Incorrect Answers
A:Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding. An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions.
B:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. Applied case: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions.
D:Choose the appropriate IPv6 transition and address-sharing model for subscriber connectivity, and test mapping state and application behavior end to end. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 142
A Cisco service provider design review finds: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions. The team proposes: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
- IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
- iBGP does not ordinarily re-advertise routes learned from one iBGP peer to another without route reflection or confederations; next-hop validation remains required.
- BGP establishes over TCP, OSPF uses protocol-specific IPv4 or IPv6 hellos and IS-IS exchanges Layer-2 link-local hellos; one protocol can work while another fails.
Explanation
Correct Answer
B:Relevant validation before approval: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes. Applied case: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions.
Incorrect Answers
A:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
C:IBGP does not ordinarily re-advertise routes learned from one iBGP peer to another without route reflection or confederations; next-hop validation remains required. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
D:This option addresses a different service provider engineering topic (Routing adjacency troubleshooting across multiple protocols) rather than the documented IS-IS wide metrics and SPF path control decision.
Question 143
The service provider operations team has not yet approved a change. Current evidence indicates: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
- Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie.
- Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
- Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers.
Explanation
Correct Answer
A:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. Confirm afterward that: Preferred paths align with declared metrics while all participating routers interpret the advertised costs consistently.
Incorrect Answers
B:Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
C:Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
D:Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 144
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions. 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.
- Preferred paths align with declared metrics while all participating routers interpret the advertised costs consistently.
- Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
- Only planned prefixes cross the protocol boundary once and core convergence remains stable under service-route churn.
- Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches.
Explanation
Correct Answer
A:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. The approved implementation step was: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
Incorrect Answers
B:Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers. An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions.
C:Only planned prefixes cross the protocol boundary once and core convergence remains stable under service-route churn. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
D:Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 145
An implementation sign-off request identifies the following problem: An operator uses a very large new metric in an area that still expects narrow metrics and creates inconsistent path decisions. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure. Verify: Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
- 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.
- Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Verify: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
- Change: Deploy route reflection with deliberate client and cluster design and preserve IGP reachability to advertised BGP next hops. Verify: Check route-reflector client relationships, originator and cluster attributes, BGP next-hop resolution and the RIB versus FIB.
Explanation
Correct Answer
C:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. The change is successful only when: Preferred paths align with declared metrics while all participating routers interpret the advertised costs consistently.
Incorrect Answers
A:Change: Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure.
B:Change: Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas.
D:Change: Deploy route reflection with deliberate client and cluster design and preserve IGP reachability to advertised BGP next hops. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 146
A service provider network engineer is reviewing this backbone or customer-service scenario: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ. A proposed shortcut is: Set every OSPF interface to a random area and disable all checks instead of identifying the actual failed adjacency stage. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection.
- Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link.
- Set every OSPF interface to a random area and disable all checks instead of identifying the actual failed adjacency stage.
- Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements.
Explanation
Correct Answer
D:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ.
Incorrect Answers
A:Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
B:This option addresses a different service provider engineering topic (IS-IS neighbor adjacency and link readiness) rather than the documented OSPFv2 neighbor state and MTU mismatch decision.
C:OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
Question 147
A Cisco service provider design review finds: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ. The team proposes: Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
- Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
- BGP establishes over TCP, OSPF uses protocol-specific IPv4 or IPv6 hellos and IS-IS exchanges Layer-2 link-local hellos; one protocol can work while another fails.
- OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
Explanation
Correct Answer
D:Demonstrable success requires: Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches. Applied case: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ.
Incorrect Answers
A:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
B:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
C:This option addresses a different service provider engineering topic (Routing adjacency troubleshooting across multiple protocols) rather than the documented OSPFv2 neighbor state and MTU mismatch decision.
Question 148
The service provider operations team has not yet approved a change. Current evidence indicates: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows.
- Compare BFD session state, negotiated intervals, packet drops and routing convergence after controlled loss and benign congestion tests.
- Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers.
- Check received and advertised BGP attributes, applied route policy, peer documentation and resulting best path for a controlled test prefix.
Explanation
Correct Answer
C:OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior. Applied case: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ.
Incorrect Answers
A:Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
B:Compare BFD session state, negotiated intervals, packet drops and routing convergence after controlled loss and benign congestion tests. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
D:Check received and advertised BGP attributes, applied route policy, peer documentation and resulting best path for a controlled test prefix. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
Question 149
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ. 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.
- 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.
- Authorized prefixes are imported or exported and unintended customer or infrastructure prefixes are rejected without adjacency disruption.
- Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family.
Explanation
Correct Answer
A:OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior. The result must be validated using the documented device, service or access context.
Incorrect Answers
B:Only planned prefixes cross the protocol boundary once and core convergence remains stable under service-route churn. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
C:Authorized prefixes are imported or exported and unintended customer or infrastructure prefixes are rejected without adjacency disruption. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
D:Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
Question 150
For an original SPCOR service-provider engineering scenario, consider: Two OSPFv2 core routers have matching hello and dead timers but stay in ExStart because their interface MTU assumptions differ. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements.
- Check: Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers.
- Check: Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses.
- Set every OSPF interface to a random area and disable all checks instead of identifying the actual failed adjacency stage.
- Change: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding.
Explanation
Correct Answer
A:OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior. Acceptance: Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches.
B:OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior. Required intervention: Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements.
Incorrect Answers
C:Check: Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
D:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
E:Change: Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding. OSPF adjacency formation progresses through distinct neighbor states; matching basic IP addresses does not resolve MTU or designated-router behavior.
