Question 240 An inbound BGP prefix list was updated, but old accepted prefixes remain until the operator performs a full neighbor reset. Which lasting design or operational safeguard best prevents this particular issue from recurring? Centralize egress local-preference policy and test best-path order when adding peers. Include underlay reachability, TTL and update-source in loopback-peering templates. Review attribute precedence whenever inbound path-manipulation route-maps change. Plan nondisruptive BGP policy refresh procedures for routine filters. ExplanationCorrect Answer D:Plan nondisruptive BGP policy refresh procedures for routine filters. This addresses the recurring cause: BGP route refresh lets a speaker reapply an inbound policy to received updates without tearing down TCP peering. A targeted acceptance check is: Verify policy changes take effect while neighbor Established uptime remains continuous. Other Answers A:Centralize egress local-preference policy and test best-path order when adding peers. BGP route refresh lets a speaker reapply an inbound policy to received updates without tearing down TCP peering. B:Include underlay reachability, TTL and update-source in loopback-peering templates. BGP route refresh lets a speaker reapply an inbound policy to received updates without tearing down TCP peering. C:Review attribute precedence whenever inbound path-manipulation route-maps change. BGP route refresh lets a speaker reapply an inbound policy to received updates without tearing down TCP peering.
Question 241 A customer's upstream route-map prepends the customer's AS on outbound announcements but the customer expects this to alter its own ingress path choice immediately. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Validate AS-path prepending from external peers and treat it as a remote-inbound influence rather than a guaranteed local choice. Activate the peer in the appropriate BGP IPv6 AF and verify relevant IPv6 network/policy statements. Correct the overriding policy before assuming AS-path length will select the path. Use supported inbound route refresh or soft policy re-evaluation before disruptive hard resets. ExplanationCorrect Answer A:Validate AS-path prepending from external peers and treat it as a remote-inbound influence rather than a guaranteed local choice. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. Compare outbound advertised AS paths and observed remote selection where visibility exists. Other Answers B:Activate the peer in the appropriate BGP IPv6 AF and verify relevant IPv6 network/policy statements. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. C:Correct the overriding policy before assuming AS-path length will select the path. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. D:Use supported inbound route refresh or soft policy re-evaluation before disruptive hard resets. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length.
Question 242 A customer's upstream route-map prepends the customer's AS on outbound announcements but the customer expects this to alter its own ingress path choice immediately. Which technical mechanism best explains the behavior observed in this scenario? Cisco weight affects only the local BGP decision and is not advertised to other routers. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. BGP evaluates local preference before AS-path length when other earlier conditions are equal. BGP transport reachability does not by itself activate exchange for every multiprotocol address family. ExplanationCorrect Answer B:AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. This explains why the initial condition produces the observed failure. The direct repair is: Validate AS-path prepending from external peers and treat it as a remote-inbound influence rather than a guaranteed local choice. Validate through: Compare outbound advertised AS paths and observed remote selection where visibility exists. Other Answers A:Cisco weight affects only the local BGP decision and is not advertised to other routers. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. C:BGP evaluates local preference before AS-path length when other earlier conditions are equal. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. D:BGP transport reachability does not by itself activate exchange for every multiprotocol address family. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length.
Question 243 A customer's upstream route-map prepends the customer's AS on outbound announcements but the customer expects this to alter its own ingress path choice immediately. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Show IPv6 unicast neighbor activation and the expected prefixes on both peers. Verify policy changes take effect while neighbor Established uptime remains continuous. Compare outbound advertised AS paths and observed remote selection where visibility exists. Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. ExplanationCorrect Answer C:Compare outbound advertised AS paths and observed remote selection where visibility exists. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. Other Answers A:Show IPv6 unicast neighbor activation and the expected prefixes on both peers. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. B:Verify policy changes take effect while neighbor Established uptime remains continuous. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. D:Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length.
Question 244 A customer's upstream route-map prepends the customer's AS on outbound announcements but the customer expects this to alter its own ingress path choice immediately. Which lasting design or operational safeguard best prevents this particular issue from recurring? Regression-test reflection and filtering for every client when modifying cluster policy. Use per-AF activation and route-policy checklists for MP-BGP sessions. Centralize egress local-preference policy and test best-path order when adding peers. Coordinate traffic engineering with upstream routing policy and verify real path impact. ExplanationCorrect Answer D:Coordinate traffic engineering with upstream routing policy and verify real path impact. This addresses the recurring cause: AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. A targeted acceptance check is: Compare outbound advertised AS paths and observed remote selection where visibility exists. Other Answers A:Regression-test reflection and filtering for every client when modifying cluster policy. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. B:Use per-AF activation and route-policy checklists for MP-BGP sessions. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length. C:Centralize egress local-preference policy and test best-path order when adding peers. AS-path prepending advertises a longer path to remote decision makers, whose other attributes may outweigh length.
Question 245 A campus PBR rule pins payment terminals to an ISP path that stays physically up after the provider loses remote reachability; IP SLA probes exist but are not tracked by the policy. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Bind the approved PBR next-hop selection to an effective tracked reachability condition and provide fallback forwarding. Inspect OSPF path type and cost instead of changing interprotocol administrative distance. Apply a narrowly scoped outbound prefix policy for the peer to include only explicitly approved networks. Place the customer-facing interface in the correct VRF and verify its dedicated routing context and interfaces. ExplanationCorrect Answer A:Bind the approved PBR next-hop selection to an effective tracked reachability condition and provide fallback forwarding. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. Fail remote reachability and verify SLA state, track transitions and payment traffic shifting to the healthy next hop. Other Answers B:Inspect OSPF path type and cost instead of changing interprotocol administrative distance. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. C:Apply a narrowly scoped outbound prefix policy for the peer to include only explicitly approved networks. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. D:Place the customer-facing interface in the correct VRF and verify its dedicated routing context and interfaces. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision.
Question 246 A campus PBR rule pins payment terminals to an ISP path that stays physically up after the provider loses remote reachability; IP SLA probes exist but are not tracked by the policy. Which technical mechanism best explains the behavior observed in this scenario? A successful IP SLA probe automatically removes a PBR next hop even when no track object is referenced. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. IP SLA measures configured end-to-end reachability and tracking can withdraw a route despite a locally up interface. An IP SLA definition without active scheduling produces no continuous probe results for dependent tracking. ExplanationCorrect Answer B:A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. This explains why the initial condition produces the observed failure. The direct repair is: Bind the approved PBR next-hop selection to an effective tracked reachability condition and provide fallback forwarding. Validate through: Fail remote reachability and verify SLA state, track transitions and payment traffic shifting to the healthy next hop. Other Answers A:IP SLA can measure a path, but it does not automatically change PBR forwarding without an explicit, supported tracking or verification binding. The described problem is that the policy still references an untracked next hop. C:IP SLA measures configured end-to-end reachability and tracking can withdraw a route despite a locally up interface. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. D:An IP SLA definition without active scheduling produces no continuous probe results for dependent tracking. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision.
Question 247 A campus PBR rule pins payment terminals to an ISP path that stays physically up after the provider loses remote reachability; IP SLA probes exist but are not tracked by the policy. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Capture the requested URL or response and verify the corrected SLA result matches the application's intended behavior. Observe operation runtime state, fresh response history and track transitions under a test outage. Fail remote reachability and verify SLA state, track transitions and payment traffic shifting to the healthy next hop. Compare jitter, latency and loss readings with the observed real-time media impairment. ExplanationCorrect Answer C:Fail remote reachability and verify SLA state, track transitions and payment traffic shifting to the healthy next hop. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. Other Answers A:Capture the requested URL or response and verify the corrected SLA result matches the application's intended behavior. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. B:Observe operation runtime state, fresh response history and track transitions under a test outage. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. D:Compare jitter, latency and loss readings with the observed real-time media impairment. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision.
Question 248 A campus PBR rule pins payment terminals to an ISP path that stays physically up after the provider loses remote reachability; IP SLA probes exist but are not tracked by the policy. Which lasting design or operational safeguard best prevents this particular issue from recurring? Monitor media-sensitive paths with performance probes rather than binary reachability alone. Document per-VRF probe identities for monitored overlays and customer routing. Audit both SLA definitions and schedules before activating tracked routing. Use track-aware PBR with documented probe targets and scheduled remote failure tests. ExplanationCorrect Answer D:Use track-aware PBR with documented probe targets and scheduled remote failure tests. This addresses the recurring cause: A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. A targeted acceptance check is: Fail remote reachability and verify SLA state, track transitions and payment traffic shifting to the healthy next hop. Other Answers A:Monitor media-sensitive paths with performance probes rather than binary reachability alone. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. B:Document per-VRF probe identities for monitored overlays and customer routing. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision. C:Audit both SLA definitions and schedules before activating tracked routing. A scheduled IP SLA probe tests remote path availability; a track object exposes that result to a route or policy decision.
Question 249 A provider edge learns an MPLS label for a customer prefix, but an engineer expects every core hop to inspect the customer's destination IP at each transition. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Trace the label-switched path and forwarding-label entries instead of assuming repeated customer-IP lookups in the core. Enable or repair the supported MPLS forwarding and label-distribution configuration on the missing core link. Separate transport label delivery from VPN service isolation and validate the applicable VRF/service labels. Validate each router's local label binding and adjacency rather than demanding one network-wide numeric label. ExplanationCorrect Answer A:Trace the label-switched path and forwarding-label entries instead of assuming repeated customer-IP lookups in the core. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. Compare incoming and outgoing labels at intermediate routers and observe delivery at the final egress. Other Answers B:Enable or repair the supported MPLS forwarding and label-distribution configuration on the missing core link. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. C:Separate transport label delivery from VPN service isolation and validate the applicable VRF/service labels. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. D:Validate each router's local label binding and adjacency rather than demanding one network-wide numeric label. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries.
Question 250 A provider edge learns an MPLS label for a customer prefix, but an engineer expects every core hop to inspect the customer's destination IP at each transition. Which technical mechanism best explains the behavior observed in this scenario? LDP label bindings rely on reachable forwarding-equivalence classes and usable transport reachability. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. Implicit-null label advertisement can request removal of the transport label at the penultimate hop to reduce egress lookup work. A complete LSP needs continuous label switching across the intended MPLS-capable path. ExplanationCorrect Answer B:MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. This explains why the initial condition produces the observed failure. The direct repair is: Trace the label-switched path and forwarding-label entries instead of assuming repeated customer-IP lookups in the core. Validate through: Compare incoming and outgoing labels at intermediate routers and observe delivery at the final egress. Other Answers A:LDP label bindings rely on reachable forwarding-equivalence classes and usable transport reachability. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. C:Implicit-null label advertisement can request removal of the transport label at the penultimate hop to reduce egress lookup work. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries. D:A complete LSP needs continuous label switching across the intended MPLS-capable path. MPLS core label-switching routers forward based on labels using swap, push or pop operations according to LFIB entries.
