Cisco 350-501 Practice Test 14
Question 130
For an original SPCOR service-provider engineering scenario, consider: A dual-stack core keeps an IS-IS IPv4 topology healthy while an IPv6 next hop is unreachable, but operations assumes identical topology guarantees IPv6 forwarding. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Check: Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
- Change: Apply documented BGP community or extended-community policies at the intended import or export point and verify resulting attribute propagation.
- Change: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data.
- Check: Inspect IS-IS neighbor state, hello capture, interface MTU and level configuration at both endpoints.
- Assume the presence of an IPv4 IS-IS neighbor proves all IPv6 prefixes and next hops are reachable without advertisements.
Explanation
Correct Answer
A:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. Required intervention: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data.
C:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. Evidence: Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
Incorrect Answers
B:This option addresses a different service provider engineering topic (BGP route-policy communities and provider preference) rather than the documented IS-IS IPv4 IPv6 single and multitopology decision.
D:Check: Inspect IS-IS neighbor state, hello capture, interface MTU and level configuration at both endpoints. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
E:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
Question 131
A service provider network engineer is reviewing this backbone or customer-service scenario: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route. A proposed shortcut is: Assume the presence of an IPv4 IS-IS neighbor proves all IPv6 prefixes and next hops are reachable without advertisements. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link.
- Assume the presence of an IPv4 IS-IS neighbor proves all IPv6 prefixes and next hops are reachable without advertisements.
- Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- 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
D:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route.
Incorrect Answers
A:Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
B:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. Applied case: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route.
C:Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
Question 132
A Cisco service provider design review finds: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route. The team proposes: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data. 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.
- 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.
- 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
A:Demonstrable success requires: Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family. Applied case: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route.
Incorrect Answers
B:Graceful restart can retain forwarding with peer help during control recovery, while NSR replicates live session state on supported dual-control-plane systems. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
C:LACP negotiates compatible members into a logical bundle while per-flow hashing commonly keeps a flow on one member to preserve packet order. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
D: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. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
Question 133
The service provider operations team has not yet approved a change. Current evidence indicates: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route. 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.
- Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie.
- Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
- Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
Explanation
Correct Answer
D:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. 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. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
B:Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
C:Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
Question 134
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route. 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.
- Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family.
- Accepted members forward correctly, aggregate capacity reflects active links and service survives an individual member failure.
- Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling.
Explanation
Correct Answer
B:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. The approved implementation step was: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data.
Incorrect Answers
A:Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
C:Accepted members forward correctly, aggregate capacity reflects active links and service survives an individual member failure. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
D:Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
Question 135
An implementation sign-off request identifies the following problem: A team enables IS-IS multi-topology IPv6 on a new PE but forgets its configured per-topology advertisements and sees no IPv6 route. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- 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.
- Change: Restrict redistribution using explicit route policy and tags, and maintain a scalable separation of service prefixes from core IGP reachability. Verify: Trace sample source routes, redistribution policy hits, tags, LSDB or LSP size and resulting RIB changes across both boundaries.
- Change: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data. Verify: Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
- Change: Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link. Verify: Inspect IS-IS neighbor state, hello capture, interface MTU and level configuration at both endpoints.
Explanation
Correct Answer
C:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. The change is successful only when: Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family.
Incorrect Answers
A:Change: Deploy route reflection with deliberate client and cluster design and preserve IGP reachability to advertised BGP next hops. Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
B:Change: Restrict redistribution using explicit route policy and tags, and maintain a scalable separation of service prefixes from core IGP reachability.
D:Change: Match IS-IS level operation and interface parameters before expecting LSP exchange and route installation across a service provider core link.
Question 136
A service provider network engineer is reviewing this backbone or customer-service scenario: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop. 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.
- Evaluate the ordered BGP decision process and set the intended local policy attribute at the correct AS boundary.
Explanation
Correct Answer
C:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop.
Incorrect Answers
A:Verify OSPFv3 interface activation, matching area and instance settings and IPv6 address-family route advertisement before expecting end-to-end forwarding. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
B:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
D:Evaluate the ordered BGP decision process and set the intended local policy attribute at the correct AS boundary. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 137
A Cisco service provider design review finds: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop. 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.
- 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 best-path selection considers local policy such as weight and local preference before several later tie breakers, including path length and MED context.
- BGP communities carry policy tags whose meaning depends on configured policy; local preference influences internal outbound selection but is not a universal external traffic-engineering instruction.
Explanation
Correct Answer
A:Relevant validation before approval: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes. Applied case: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop.
Incorrect Answers
B: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.
C:BGP best-path selection considers local policy such as weight and local preference before several later tie breakers, including path length and MED context. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
D:BGP communities carry policy tags whose meaning depends on configured policy; local preference influences internal outbound selection but is not a universal external traffic-engineering instruction. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 138
The service provider operations team has not yet approved a change. Current evidence indicates: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop. 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.
- Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows.
- Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
Explanation
Correct Answer
D:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. Applied case: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop.
Incorrect Answers
A: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.
B:Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
C:Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
Question 139
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A carrier upgrades an Ethernet backbone but leaves IS-IS link metrics uniform so latency-sensitive routes still take an expensive lower-capacity hop. 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.
- Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling.
- Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
- Preferred paths align with declared metrics while all participating routers interpret the advertised costs consistently.
Explanation
Correct Answer
D:IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs. The result must be validated using the documented device, service or access context.
Incorrect Answers
A:Genuine path loss is detected promptly while minor delay variation does not trigger avoidable adjacency resets. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
B:Authorized IPv6 and shared-IPv4 applications work with correct port mappings, accountability and predictable failure handling. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
C:Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers. IS-IS SPF selects routes using cumulative link metrics; wide metric support and consistent advertisements matter in modern core designs.
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.
