Question 210 An ISP sends two routes with different MED values from different neighboring AS numbers; the customer assumes the lower MED always wins. 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. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. BGP transport reachability does not by itself activate exchange for every multiprotocol address family. BGP next-hop resolution is a prerequisite for installing an otherwise valid received path into the RIB. ExplanationCorrect Answer B:Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. This explains why the initial condition produces the observed failure. The direct repair is: Do not force a MED comparison across different neighboring ASes without an explicit, supported design decision. Validate through: Inspect neighboring AS values and compare the selected path under the approved MED policy. Other Answers A:Cisco weight affects only the local BGP decision and is not advertised to other routers. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. C:BGP transport reachability does not by itself activate exchange for every multiprotocol address family. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. D:BGP next-hop resolution is a prerequisite for installing an otherwise valid received path into the RIB. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions.
Question 211 An ISP sends two routes with different MED values from different neighboring AS numbers; the customer assumes the lower MED always wins. 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. Test TCP/179 reachability and verify Established state sourced from the intended loopbacks. Inspect neighboring AS values and compare the selected path under the approved MED policy. Compare outbound advertised AS paths and observed remote selection where visibility exists. ExplanationCorrect Answer C:Inspect neighboring AS values and compare the selected path under the approved MED policy. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. Other Answers A:Show IPv6 unicast neighbor activation and the expected prefixes on both peers. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. B:Test TCP/179 reachability and verify Established state sourced from the intended loopbacks. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. D:Compare outbound advertised AS paths and observed remote selection where visibility exists. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions.
Question 212 An ISP sends two routes with different MED values from different neighboring AS numbers; the customer assumes the lower MED always wins. Which lasting design or operational safeguard best prevents this particular issue from recurring? Review attribute precedence whenever inbound path-manipulation route-maps change. Plan nondisruptive BGP policy refresh procedures for routine filters. Document whether traffic-engineering policy is local-only or AS-wide before choosing attributes. Use MED only where its comparison scope and inbound path attributes are intentionally defined. ExplanationCorrect Answer D:Use MED only where its comparison scope and inbound path attributes are intentionally defined. This addresses the recurring cause: Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. A targeted acceptance check is: Inspect neighboring AS values and compare the selected path under the approved MED policy. Other Answers A:Review attribute precedence whenever inbound path-manipulation route-maps change. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. B:Plan nondisruptive BGP policy refresh procedures for routine filters. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. C:Document whether traffic-engineering policy is local-only or AS-wide before choosing attributes. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions.
Question 213 An iBGP route learned by an internal router is not passed to another iBGP peer in a full-mesh-free topology. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Introduce the approved route-reflector client relationship or build required full-mesh sessions. Validate AS-path prepending from external peers and treat it as a remote-inbound influence rather than a guaranteed local choice. Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Set the correct loopback `update-source` and peer address consistently on both ends. ExplanationCorrect Answer A:Introduce the approved route-reflector client relationship or build required full-mesh sessions. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Other Answers B:Validate AS-path prepending from external peers and treat it as a remote-inbound influence rather than a guaranteed local choice. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. C:Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. D:Set the correct loopback `update-source` and peer address consistently on both ends. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design.
Question 214 An iBGP route learned by an internal router is not passed to another iBGP peer in a full-mesh-free topology. Which technical mechanism best explains the behavior observed in this scenario? BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. Multihop eBGP peering over loopbacks requires packet reachability and TTL/configuration beyond a directly connected peer assumption. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. ExplanationCorrect Answer B:Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. This explains why the initial condition produces the observed failure. The direct repair is: Introduce the approved route-reflector client relationship or build required full-mesh sessions. Validate through: Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Other Answers A:BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. C:Multihop eBGP peering over loopbacks requires packet reachability and TTL/configuration beyond a directly connected peer assumption. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. D:A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design.
Question 215 An iBGP route learned by an internal router is not passed to another iBGP peer in a full-mesh-free topology. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Verify policy changes take effect while neighbor Established uptime remains continuous. Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Check local-pref values and the selected best path on internal BGP speakers. ExplanationCorrect Answer C:Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. Other Answers A:Verify policy changes take effect while neighbor Established uptime remains continuous. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. B:Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. D:Check local-pref values and the selected best path on internal BGP speakers. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design.
Question 216 An iBGP route learned by an internal router is not passed to another iBGP peer in a full-mesh-free topology. Which lasting design or operational safeguard best prevents this particular issue from recurring? Coordinate traffic engineering with upstream routing policy and verify real path impact. Use MED only where its comparison scope and inbound path attributes are intentionally defined. Plan nondisruptive BGP policy refresh procedures for routine filters. Maintain explicit route-reflector topology and client inventory. ExplanationCorrect Answer D:Maintain explicit route-reflector topology and client inventory. This addresses the recurring cause: Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. A targeted acceptance check is: Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Other Answers A:Coordinate traffic engineering with upstream routing policy and verify real path impact. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. B:Use MED only where its comparison scope and inbound path attributes are intentionally defined. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design. C:Plan nondisruptive BGP policy refresh procedures for routine filters. Standard iBGP does not advertise an iBGP-learned route to another iBGP peer without a reflection or confederation design.
Question 217 A route reflector receives two paths from clients but one downstream client lacks a necessary route after reflection policy changes. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Validate route-reflector client configuration and outbound policy for the missing prefix. Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Find the policy or topology that reintroduced the upstream's AS rather than disabling the loop check as a routine fix. Do not force a MED comparison across different neighboring ASes without an explicit, supported design decision. ExplanationCorrect Answer A:Validate route-reflector client configuration and outbound policy for the missing prefix. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Other Answers B:Use an AS-propagated attribute such as local preference instead of relying on router-local weight. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. C:Find the policy or topology that reintroduced the upstream's AS rather than disabling the loop check as a routine fix. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. D:Do not force a MED comparison across different neighboring ASes without an explicit, supported design decision. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection.
Question 218 A route reflector receives two paths from clients but one downstream client lacks a necessary route after reflection policy changes. Which technical mechanism best explains the behavior observed in this scenario? BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. A BGP TCP connection uses the configured source IP; mismatched source and peer address can invalidate or destabilize a session. Multihop eBGP peering over loopbacks requires packet reachability and TTL/configuration beyond a directly connected peer assumption. ExplanationCorrect Answer B:A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. This explains why the initial condition produces the observed failure. The direct repair is: Validate route-reflector client configuration and outbound policy for the missing prefix. Validate through: Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Other Answers A:BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. C:A BGP TCP connection uses the configured source IP; mismatched source and peer address can invalidate or destabilize a session. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. D:Multihop eBGP peering over loopbacks requires packet reachability and TTL/configuration beyond a directly connected peer assumption. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection.
Question 219 A route reflector receives two paths from clients but one downstream client lacks a necessary route after reflection policy changes. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Inspect next-hop reachability and confirm a formerly inaccessible BGP prefix becomes valid and installed. Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Inspect the advertised AS_PATH and ensure corrected updates no longer contain a prohibited loop. ExplanationCorrect Answer C:Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. Other Answers A:Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. B:Inspect next-hop reachability and confirm a formerly inaccessible BGP prefix becomes valid and installed. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. D:Inspect the advertised AS_PATH and ensure corrected updates no longer contain a prohibited loop. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection.
Question 220 A route reflector receives two paths from clients but one downstream client lacks a necessary route after reflection policy changes. Which lasting design or operational safeguard best prevents this particular issue from recurring? Use per-AF activation and route-policy checklists for MP-BGP sessions. Include end-to-end BGP next-hop reachability tests during iBGP rollouts. Use MED only where its comparison scope and inbound path attributes are intentionally defined. Regression-test reflection and filtering for every client when modifying cluster policy. ExplanationCorrect Answer D:Regression-test reflection and filtering for every client when modifying cluster policy. This addresses the recurring cause: A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. A targeted acceptance check is: Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Other Answers A:Use per-AF activation and route-policy checklists for MP-BGP sessions. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. B:Include end-to-end BGP next-hop reachability tests during iBGP rollouts. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. C:Use MED only where its comparison scope and inbound path attributes are intentionally defined. A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection.
