CCNP Practice Question: Is troubleshooting a BGP issue where a router is…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  The route with higher local preference has a lower weight than the current best path.

  Why this is correct

  Cisco's BGP best-path algorithm evaluates weight first; the highest weight always wins. Since the current best path has a higher weight, it remains selected regardless of local preference, because local preference is only compared after weights are found equal. Thus a higher local preference cannot make a lower-weight route the best path.

• ✗

  The route with higher local preference has a higher MED value.

  Why it's wrong here

  MED is not considered until later in the path-selection process, after AS_PATH length and origin are compared. Because local preference is evaluated at step 2 and MED is evaluated at step 6, a route with higher local preference would be selected before MED is ever examined. Additionally, a higher MED is actually less preferred, since lower MED is better, but this attribute is never reached when the LP tiebreaker has already decided.

• ✗

  The route with higher local preference is not synchronized with IGP.

  Why it's wrong here

  BGP synchronization is an old IOS rule requiring an iBGP-learned route to also be present in the IGP before it is advertised to eBGP; it is disabled by default and does not participate in best-path selection. A route that fails synchronization would be deemed invalid and excluded from the RIB, not simply ranked behind the current best path. Since local preference is checked during best-path selection, an unsynchronized route cannot be 'best' with higher LP while the current best path remains valid; the unsynchronized route would be ineligible regardless of LP.

• ✗

  The route with higher local preference was learned from an eBGP peer, while the current best path is from an iBGP peer.

  Why it's wrong here

  Route source (eBGP versus iBGP) is only compared much later in BGP's decision process, after weight, local preference, AS-path length, origin, and MED. If the candidate has a higher local preference, it would win at the LP step, before the source type is ever evaluated. In fact, eBGP is preferred over iBGP when all earlier steps tie, so learning the higher-LP route from eBGP would make it even more likely to become best, not explain why it loses.