Cisco 350-501 Practice Test 30
Question 290
For an original SPCOR service-provider engineering scenario, consider: A service provider performs a route processor switchover and expects zero control-plane churn although the software image does not support session preservation. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Check: Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers.
- Check: Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
- Change: Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure.
- Assume a redundant supervisor automatically provides nonstop protocol sessions and unlimited graceful forwarding with no platform configuration.
Explanation
Correct Answer
C:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Acceptance: Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
D:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Evidence: Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
Incorrect Answers
A:Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
B:Check: Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
E:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
Question 291
A service provider network engineer is reviewing this backbone or customer-service scenario: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure. A proposed shortcut is: Assume a redundant supervisor automatically provides nonstop protocol sessions and unlimited graceful forwarding with no platform configuration. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure.
- Assume a redundant supervisor automatically provides nonstop protocol sessions and unlimited graceful forwarding with no platform configuration.
- 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
B:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure.
Incorrect Answers
A:Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
C:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Applied case: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure.
D:Choose the appropriate IPv6 transition and address-sharing model for subscriber connectivity, and test mapping state and application behavior end to end. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
Question 292
A Cisco service provider design review finds: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure. The team proposes: Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
- LACP negotiates compatible members into a logical bundle while per-flow hashing commonly keeps a flow on one member to preserve packet order.
- IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
- BGP best-path selection considers local policy such as weight and local preference before several later tie breakers, including path length and MED context.
Explanation
Correct Answer
A:Demonstrable success requires: Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers. Applied case: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure.
Incorrect Answers
B: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.
C:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure.
D:BGP best-path selection considers local policy such as weight and local preference before several later tie breakers, including path length and MED context. An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure.
Question 293
The service provider operations team has not yet approved a change. Current evidence indicates: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
- Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
- Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows.
- Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
Explanation
Correct Answer
B:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Confirm afterward that: Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
Incorrect Answers
A:Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
C:Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
D:This option addresses a different service provider engineering topic (IS-IS IPv4 IPv6 single and multitopology) rather than the documented Graceful restart NSR and maintenance continuity decision.
Question 294
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure. 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.
- Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
- Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling.
- Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
- Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches.
Explanation
Correct Answer
A:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. The approved implementation step was: Configure high availability features with supported peer behavior and validate which control and forwarding states are preserved during process or RP failure.
Incorrect Answers
B:Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
C:Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
D:Expected neighbors reach the appropriate full adjacency state and exchange synchronized LSDB information without hidden MTU mismatches. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
Question 295
An implementation sign-off request identifies the following problem: An engineer enables graceful restart on one BGP router without checking neighbors' helper capability and stale-route timer implications during a control failure. 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: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Verify: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- 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: Tune consistent OSPF cost or reference-bandwidth settings and validate reconvergence under controlled link failures. Verify: Record each link cost and LSDB view, calculate expected shortest paths and compare route changes during shut and no-shut tests.
Explanation
Correct Answer
A:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. The change is successful only when: Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
Incorrect Answers
B:Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
C:Change: Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
D:Change: Tune consistent OSPF cost or reference-bandwidth settings and validate reconvergence under controlled link failures. Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems.
Question 296
A service provider network engineer is reviewing this backbone or customer-service scenario: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss. A proposed shortcut is: Set one-millisecond BFD probes on every congested platform and assume all peers support the timers without negotiation. 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.
- Choose the appropriate IPv6 transition and address-sharing model for subscriber connectivity, and test mapping state and application behavior end to end.
- Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Set one-millisecond BFD probes on every congested platform and assume all peers support the timers without negotiation.
Explanation
Correct Answer
A:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss.
Incorrect Answers
B:Choose the appropriate IPv6 transition and address-sharing model for subscriber connectivity, and test mapping state and application behavior end to end. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
C:Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
D:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
Question 297
A Cisco service provider design review finds: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss. The team proposes: Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
- Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
- BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
- 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
C:Demonstrable success requires: Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets. Applied case: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss.
Incorrect Answers
A:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
B:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
D:This option addresses a different service provider engineering topic (OSPF multiarea ABR area types and route summarization) rather than the documented BFD rapid fault detection and link stability decision.
Question 298
The service provider operations team has not yet approved a change. Current evidence indicates: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Compare BFD session state, negotiated intervals, packet drops and routing convergence after controlled loss and benign congestion tests.
- Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures.
- Inspect IS-IS neighbor state, hello capture, interface MTU and level configuration at both endpoints.
- Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence.
Explanation
Correct Answer
A:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. Applied case: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss.
Incorrect Answers
B:Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
C:Inspect IS-IS neighbor state, hello capture, interface MTU and level configuration at both endpoints. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
D:Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
Question 299
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss. 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.
- Accepted members forward correctly, aggregate capacity reflects active links and service survives an individual member failure.
- Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries.
- Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets.
- Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family.
Explanation
Correct Answer
C:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. The result must be validated using the documented device, service or access context.
Incorrect Answers
A:Accepted members forward correctly, aggregate capacity reflects active links and service survives an individual member failure. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
B:Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
D:Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
Question 300
For an original SPCOR service-provider engineering scenario, consider: A carrier route traverses a bundle member that failed silently, while long IGP hello timers delay the detection of forwarding loss. Select THREE compatible elements: a proper correction, a targeted diagnostic and an acceptance result.
- Result: Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets.
- Result: Stable OSPFv3 adjacencies advertise the intended IPv6 prefixes with reachable next hops.
- Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Check: Inspect BGP neighbor transport state, local and remote AS, update source, TCP reachability and IPv4 or IPv6 address-family activation.
- Change: Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection.
- Check: Compare BFD session state, negotiated intervals, packet drops and routing convergence after controlled loss and benign congestion tests.
Explanation
Correct Answer
A:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. Required intervention: Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection.
E:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. Acceptance: Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets.
F:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. Compare BFD session state, negotiated intervals, packet drops and routing convergence after controlled loss and benign congestion tests.
Incorrect Answers
B:Result: Stable OSPFv3 adjacencies advertise the intended IPv6 prefixes with reachable next hops. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
C:Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
D:Check: Inspect BGP neighbor transport state, local and remote AS, update source, TCP reachability and IPv4 or IPv6 address-family activation. BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
