State the BGP route selection process in order.

• A. Highest weight, highest local preference, locally generated route, shortest as-path, lowest origin, lowest MED, prefer EBGP route over IBGP
• B. Highest weight, shortest as-path, locally generated route, highest local preference, lowest origin, lowest MED, prefer EBGP route over IBGP
• C. Highest weight, highest local preference, shortest as-path, locally generated route, lowest origin, MED, prefer EBGP route over IBGP
• D. Highest weight, highest local preference, shortest as-path, MED, lowest origin, locally generated route, prefer EBGP route over IBGP

Answer: (A)

BGP picks the best path by applying a fixed sequence of attribute-based checks, starting with local, router-specific preferences and moving toward global reachability information. The first target is the weight, a Cisco-specific, non-propagated tiebreaker that lives only on the local router; pushing higher weight up front makes that route locally preferred. If weights tie, the next criterion is the local preference value, which is propagated inside the AS and signals which exit point the AS prefers; higher local preference wins.

Next, locally originated routes are favored over those learned from neighbors, ensuring routes injected by this router (via network statements, aggregate, or redistribution) are preferred before external ones. Once that distinction is made, the path with the shortest AS path is chosen, because fewer hops generally means a simpler, faster path with fewer potential points of failure. If several paths share the same AS-path length, the route with the lower origin type is preferred: IGP-originated routes are favored over EGP-originated or incomplete origins, reflecting how the route was originally learned or injected.

After origin, the lower MED (Multi-Exit Discriminator) value is considered; MED acts as a hint to external neighbors about the preferred entry point into the AS, with a smaller value indicating a preferable path entry. Finally, if everything else is equal, an EBGP-learned route is preferred over an IBGP-learned one, reflecting the inherent trust and directness of routes learned from outside the AS.

This sequence matches the standard ordering: weight, local preference, locally originated, shortest AS-path, lowest origin, MED, then EBGP over IBGP.