Question 200 Two eBGP exit routers learn the same prefix with different local preferences; traffic exits through the backup despite a shorter AS path on the primary. Which lasting design or operational safeguard best prevents this particular issue from recurring? Include end-to-end BGP next-hop reachability tests during iBGP rollouts. Plan nondisruptive BGP policy refresh procedures for routine filters. Include underlay reachability, TTL and update-source in loopback-peering templates. Centralize egress local-preference policy and test best-path order when adding peers. ExplanationCorrect Answer D:Centralize egress local-preference policy and test best-path order when adding peers. This addresses the recurring cause: BGP evaluates local preference before AS-path length when other earlier conditions are equal. A targeted acceptance check is: Check local-pref values and the selected best path on internal BGP speakers. Other Answers A:Include end-to-end BGP next-hop reachability tests during iBGP rollouts. BGP evaluates local preference before AS-path length when other earlier conditions are equal. B:Plan nondisruptive BGP policy refresh procedures for routine filters. BGP evaluates local preference before AS-path length when other earlier conditions are equal. C:Include underlay reachability, TTL and update-source in loopback-peering templates. BGP evaluates local preference before AS-path length when other earlier conditions are equal.
Question 201 One branch router locally sets a high Cisco BGP weight for a route but other routers in the AS still choose the original exit. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Activate the peer in the appropriate BGP IPv6 AF and verify relevant IPv6 network/policy statements. Introduce the approved route-reflector client relationship or build required full-mesh sessions. Validate route-reflector client configuration and outbound policy for the missing prefix. ExplanationCorrect Answer A:Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Cisco weight affects only the local BGP decision and is not advertised to other routers. Compare best paths on the configured router and a different iBGP router after changing local preference. Other Answers B:Activate the peer in the appropriate BGP IPv6 AF and verify relevant IPv6 network/policy statements. Cisco weight affects only the local BGP decision and is not advertised to other routers. C:Introduce the approved route-reflector client relationship or build required full-mesh sessions. Cisco weight affects only the local BGP decision and is not advertised to other routers. D:Validate route-reflector client configuration and outbound policy for the missing prefix. Cisco weight affects only the local BGP decision and is not advertised to other routers.
Question 202 One branch router locally sets a high Cisco BGP weight for a route but other routers in the AS still choose the original exit. Which technical mechanism best explains the behavior observed in this scenario? Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. Cisco weight affects only the local BGP decision and is not advertised to other routers. 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. ExplanationCorrect Answer B:Cisco weight affects only the local BGP decision and is not advertised to other routers. This explains why the initial condition produces the observed failure. The direct repair is: Use an AS-propagated attribute such as local preference instead of relying on router-local weight. Validate through: Compare best paths on the configured router and a different iBGP router after changing local preference. Other Answers A:Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. Cisco weight affects only the local BGP decision and is not advertised to other routers. C:A BGP TCP connection uses the configured source IP; mismatched source and peer address can invalidate or destabilize a session. Cisco weight affects only the local BGP decision and is not advertised to other routers. D:A reflector advertises eligible routes according to its client relationships and filtering; client configuration changes can suppress expected reflection. Cisco weight affects only the local BGP decision and is not advertised to other routers.
Question 203 One branch router locally sets a high Cisco BGP weight for a route but other routers in the AS still choose the original exit. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Test TCP/179 reachability and verify Established state sourced from the intended loopbacks. Compare best paths on the configured router and a different iBGP router after changing local preference. Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. ExplanationCorrect Answer C:Compare best paths on the configured router and a different iBGP router after changing local preference. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: Cisco weight affects only the local BGP decision and is not advertised to other routers. Other Answers A:Check BGP advertised-routes toward the missing client and the corresponding route-reflector state. Cisco weight affects only the local BGP decision and is not advertised to other routers. B:Test TCP/179 reachability and verify Established state sourced from the intended loopbacks. Cisco weight affects only the local BGP decision and is not advertised to other routers. D:Confirm the reflected prefix and ORIGINATOR_ID/CLUSTER_LIST handling where relevant. Cisco weight affects only the local BGP decision and is not advertised to other routers.
Question 204 One branch router locally sets a high Cisco BGP weight for a route but other routers in the AS still choose the original exit. 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 end-to-end BGP next-hop reachability tests during iBGP rollouts. Maintain explicit route-reflector topology and client inventory. Document whether traffic-engineering policy is local-only or AS-wide before choosing attributes. ExplanationCorrect Answer D:Document whether traffic-engineering policy is local-only or AS-wide before choosing attributes. This addresses the recurring cause: Cisco weight affects only the local BGP decision and is not advertised to other routers. A targeted acceptance check is: Compare best paths on the configured router and a different iBGP router after changing local preference. Other Answers A:Centralize egress local-preference policy and test best-path order when adding peers. Cisco weight affects only the local BGP decision and is not advertised to other routers. B:Include end-to-end BGP next-hop reachability tests during iBGP rollouts. Cisco weight affects only the local BGP decision and is not advertised to other routers. C:Maintain explicit route-reflector topology and client inventory. Cisco weight affects only the local BGP decision and is not advertised to other routers.
Question 205 Two eBGP paths have equal preference and origin but different AS-path lengths; the longer path keeps winning because a route-map sets higher local preference on it. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Correct the overriding policy before assuming AS-path length will select the path. Validate route-reflector client configuration and outbound policy for the missing prefix. Find the policy or topology that reintroduced the upstream's AS rather than disabling the loop check as a routine fix. Introduce the approved route-reflector client relationship or build required full-mesh sessions. ExplanationCorrect Answer A:Correct the overriding policy before assuming AS-path length will select the path. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. Compare the full path attributes, then demonstrate the expected winner after removing the unintended override. Other Answers B:Validate route-reflector client configuration and outbound policy for the missing prefix. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. C:Find the policy or topology that reintroduced the upstream's AS rather than disabling the loop check as a routine fix. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. D:Introduce the approved route-reflector client relationship or build required full-mesh sessions. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length.
Question 206 Two eBGP paths have equal preference and origin but different AS-path lengths; the longer path keeps winning because a route-map sets higher local preference on it. Which technical mechanism best explains the behavior observed in this scenario? AS-path length is always the first BGP comparison, even when a route-map changes local preference. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. BGP's AS-path loop-prevention check rejects routes that include the receiving router's own AS by default. Cisco weight affects only the local BGP decision and is not advertised to other routers. ExplanationCorrect Answer B:BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. This explains why the initial condition produces the observed failure. The direct repair is: Correct the overriding policy before assuming AS-path length will select the path. Validate through: Compare the full path attributes, then demonstrate the expected winner after removing the unintended override. Other Answers A:That reverses Cisco BGP best-path precedence. When earlier criteria tie, higher local preference is compared ahead of AS-path length; a policy can therefore make the longer AS path win. C:BGP's AS-path loop-prevention check rejects routes that include the receiving router's own AS by default. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. D:Cisco weight affects only the local BGP decision and is not advertised to other routers. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length.
Question 207 Two eBGP paths have equal preference and origin but different AS-path lengths; the longer path keeps winning because a route-map sets higher local preference on it. After applying the correction, which verification evidence most directly demonstrates that this issue is resolved? Inspect neighboring AS values and compare the selected path under the approved MED policy. Inspect neighbor connection details for matching local/remote addresses and stable Established uptime. Compare the full path attributes, then demonstrate the expected winner after removing the unintended override. Show IPv6 unicast neighbor activation and the expected prefixes on both peers. ExplanationCorrect Answer C:Compare the full path attributes, then demonstrate the expected winner after removing the unintended override. This checks the affected traffic or control-plane behavior, not merely a generic up/down indicator. The underlying mechanism is: BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. Other Answers A:Inspect neighboring AS values and compare the selected path under the approved MED policy. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. B:Inspect neighbor connection details for matching local/remote addresses and stable Established uptime. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. D:Show IPv6 unicast neighbor activation and the expected prefixes on both peers. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length.
Question 208 Two eBGP paths have equal preference and origin but different AS-path lengths; the longer path keeps winning because a route-map sets higher local preference on it. Which lasting design or operational safeguard best prevents this particular issue from recurring? 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. Coordinate traffic engineering with upstream routing policy and verify real path impact. Review attribute precedence whenever inbound path-manipulation route-maps change. ExplanationCorrect Answer D:Review attribute precedence whenever inbound path-manipulation route-maps change. This addresses the recurring cause: BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. A targeted acceptance check is: Compare the full path attributes, then demonstrate the expected winner after removing the unintended override. Other Answers A:Use MED only where its comparison scope and inbound path attributes are intentionally defined. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. B:Regression-test reflection and filtering for every client when modifying cluster policy. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length. C:Coordinate traffic engineering with upstream routing policy and verify real path impact. BGP stops at the first differentiating higher-priority best-path attribute, including local preference before AS-path length.
Question 209 An ISP sends two routes with different MED values from different neighboring AS numbers; the customer assumes the lower MED always wins. Which corrective action most directly resolves the documented failure without suppressing unrelated safeguards? Do not force a MED comparison across different neighboring ASes without an explicit, supported design decision. Set the correct loopback `update-source` and peer address consistently on both ends. Introduce the approved route-reflector client relationship or build required full-mesh sessions. Validate route-reflector client configuration and outbound policy for the missing prefix. ExplanationCorrect Answer A:Do not force a MED comparison across different neighboring ASes without an explicit, supported design decision. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. Inspect neighboring AS values and compare the selected path under the approved MED policy. Other Answers B:Set the correct loopback `update-source` and peer address consistently on both ends. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. C:Introduce the approved route-reflector client relationship or build required full-mesh sessions. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions. D:Validate route-reflector client configuration and outbound policy for the missing prefix. Cisco BGP ordinarily compares MED only among paths received from the same neighboring AS, subject to configuration exceptions.
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.
