A police records bureau compares multiple BGP paths to a SaaS exit and must recall the classic best-path decision order at ENARSI depth. Which early sequence is correct?
Select an answer to reveal the explanation.
Short Explanation
Cisco's early BGP beauty contest starts local: Weight, then Local Preference, then whether the path was locally originated, then shortest AS path. Only after those early steps do Origin, MED, and the later tie-breakers matter. Memorize that front half for SaaS exit troubleshooting.
Full Explanation
A police records bureau comparing multiple BGP paths to a SaaS exit at ENARSI depth must recall Cisco’s classic early best-path order: prefer highest Weight, then highest Local Preference, then prefer locally originated paths, then prefer the shortest AS path—before later tie-breakers such as Origin, MED, eBGP over iBGP, IGP metric to next hop, and router ID. Weight is Cisco-proprietary and local to the router; local preference is significant across iBGP inside the AS; locally originated beats learned paths; AS-path length is the first widespread “external distance” style comparison. That early sequence is why the correct option matches ENARSI expectations. Preferring longest AS path first, then lowest Weight, then lowest Local Preference reverses both the AS-path rule and the Weight/local-pref higher-wins rules. Preferring lowest MED first in all cases while ignoring Weight and Local Preference skips earlier steps and overstates MED’s position. Preferring the oldest route only while skipping Weight and Local Preference jumps to a late tie-breaker and ignores the attributes that usually decide SaaS exit choice first. Exam caveat: after AS path come Origin (IGP < EGP < incomplete), lowest MED (with rules/always-compare caveats), eBGP over iBGP, lowest IGP metric to BGP next hop, then oldest path / lowest RID / shortest cluster list depending on platform details—memorize early steps cold. Operational check: for competing SaaS paths, show ip bgp <prefix> and walk Weight → Local Pref → local origin → AS path before changing later attributes; document which step decided the winner for change-control evidence.