Cisco 350-501 Practice Test 24
Question 230
For an original SPCOR service-provider engineering scenario, consider: A multihomed provider wants remote traffic to prefer a particular link but assumes adding MED to one route controls every third-party autonomous system. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives.
- Guarantee every independent internet AS will honor one MED or prepend irrespective of its own routing policy.
- Check: Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family.
- Check: Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
Explanation
Correct Answer
A:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. Acceptance: Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint.
D:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. Required intervention: Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives.
Incorrect Answers
B:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
C:Check: Compare IS-IS IPv4 and IPv6 LSP TLVs, topology IDs, next-hop tables and controlled ping tests for each family. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
E:This option addresses a different service provider engineering topic (BGP Additional Paths PIC and fast failover) rather than the documented BGP MED AS_PATH prepending and ingress steering decision.
Question 231
A service provider network engineer is reviewing this backbone or customer-service scenario: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup. A proposed shortcut is: Guarantee every independent internet AS will honor one MED or prepend irrespective of its own routing policy. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Guarantee every independent internet AS will honor one MED or prepend irrespective of its own routing policy.
- Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives.
- 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.
Explanation
Correct Answer
C:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
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. Applied case: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
B:Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
D: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. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
Question 232
A Cisco service provider design review finds: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup. The team proposes: Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
- MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
- BGP TCP sessions depend on correct peer identity and routed transport; external versus internal peer behavior changes next-hop and forwarding assumptions.
- BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures.
Explanation
Correct Answer
B:Demonstrable success requires: Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint. Applied case: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
Incorrect Answers
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. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
C:BGP TCP sessions depend on correct peer identity and routed transport; external versus internal peer behavior changes next-hop and forwarding assumptions. An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
D:BFD detects data-path forwarding failure independently of slower routing hellos but extreme timer settings can create false failures. An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
Question 233
The service provider operations team has not yet approved a change. Current evidence indicates: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
- Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram.
- Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures.
Explanation
Correct Answer
C:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. Confirm afterward that: Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint.
Incorrect Answers
A:Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
B:Examine NET values, level adjacency state, LSP originator IDs and intended area boundaries on a two-area diagram. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
D:This option addresses a different service provider engineering topic (NAT64 CGNAT MAP-T DS-Lite and transition selection) rather than the documented BGP MED AS_PATH prepending and ingress steering decision.
Question 234
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup. 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.
- The preferred transit path wins for documented policy reasons without unexpected route filtering or next-hop failure.
- Selected paths follow intended costs and the backup route takes over safely after a neighbor or link failure.
- Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint.
- Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries.
Explanation
Correct Answer
C:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. The approved implementation step was: Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives.
Incorrect Answers
A:The preferred transit path wins for documented policy reasons without unexpected route filtering or next-hop failure. An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup.
B:Selected paths follow intended costs and the backup route takes over safely after a neighbor or link failure. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
D:Unique node identities produce the intended L1 or L2 adjacencies and routes cross only supported level boundaries. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
Question 235
An implementation sign-off request identifies the following problem: An operator prepends its AS number on one announcement but changes it on the wrong neighbor and unexpectedly shifts inbound flows to a backup. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Choose documented BGP ingress-traffic engineering signals and verify how relevant peers actually compare received alternatives. Verify: Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Change: Apply documented BGP community or extended-community policies at the intended import or export point and verify resulting attribute propagation. Verify: Check received and advertised BGP attributes, applied route policy, peer documentation and resulting best path for a controlled test prefix.
- 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.
Explanation
Correct Answer
A:MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences. The change is successful only when: Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint.
Incorrect Answers
B:This option addresses a different service provider engineering topic (BGP route-policy communities and provider preference) rather than the documented BGP MED AS_PATH prepending and ingress steering decision.
C:This option addresses a different service provider engineering topic (BGP OSPF and IS-IS redistribution route loop control) rather than the documented BGP MED AS_PATH prepending and ingress steering decision.
D:Change: Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data. MED influences comparisons under specific BGP decision contexts, and AS_PATH prepending is advisory because remote networks may apply their own preferences.
Question 236
A service provider network engineer is reviewing this backbone or customer-service scenario: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. A proposed shortcut is: Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support. 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.
- Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support.
- Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas.
- Restrict redistribution using explicit route policy and tags, and maintain a scalable separation of service prefixes from core IGP reachability.
Explanation
Correct Answer
A:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity.
Incorrect Answers
B:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
C:Assign unique IS-IS system IDs and consistent area identifiers for Level-1 adjacency, with proper Level-2 reachability across areas. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Restrict redistribution using explicit route policy and tags, and maintain a scalable separation of service prefixes from core IGP reachability. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 237
A Cisco service provider design review finds: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. The team proposes: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
- iBGP does not ordinarily re-advertise routes learned from one iBGP peer to another without route reflection or confederations; next-hop validation remains required.
- Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
- NAT64 translates between IPv6 and IPv4 with suitable discovery, while DS-Lite tunnels subscriber IPv4 over IPv6 to a shared CGN function; MAP-T uses different translation rules.
Explanation
Correct Answer
A:Demonstrable success requires: Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails. This principle explains the proposed technical approach, which is: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
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. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
C:This option addresses a different service provider engineering topic (IOS XR route policy language and Cisco route maps) rather than the documented BGP Additional Paths PIC and fast failover decision.
D:NAT64 translates between IPv6 and IPv4 with suitable discovery, while DS-Lite tunnels subscriber IPv4 over IPv6 to a shared CGN function; MAP-T uses different translation rules. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 238
The service provider operations team has not yet approved a change. Current evidence indicates: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Check received and advertised BGP attributes, applied route policy, peer documentation and resulting best path for a controlled test prefix.
- Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change.
- Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses.
Explanation
Correct Answer
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Applied case: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity.
Incorrect Answers
A:Check received and advertised BGP attributes, applied route policy, peer documentation and resulting best path for a controlled test prefix. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
B:Examine advertised route attributes per peer, remote looking-glass paths and measured ingress flows before and after the change. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 239
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. 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.
- Clients receive intended routes without reflection loops and installed paths resolve to reachable transport next hops.
- Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers.
- Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
- Stub or normal areas receive only intended advertisements and no unreachable discontiguous summary is treated as valid service connectivity.
Explanation
Correct Answer
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. The approved implementation step was: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
Incorrect Answers
A:Clients receive intended routes without reflection loops and installed paths resolve to reachable transport next hops. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
B:Failure recovery stays within service limits and no stale unvalidated forwarding state persists beyond documented timers. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Stub or normal areas receive only intended advertisements and no unreachable discontiguous summary is treated as valid service connectivity. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 240
For an original SPCOR service-provider engineering scenario, consider: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. 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: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Check: Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures.
- Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support.
Explanation
Correct Answer
B:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Required intervention: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Acceptance: Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
Incorrect Answers
A:Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Check: Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
E:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
