City hall enabled Flexible NetFlow, but the collector shows no new flows. Which verification focus is most relevant?
Select an answer to reveal the explanation.
Short Explanation
If the turnstile counter never phones home, the scoreboard stays blank. Check that the exporter can reach the collector and that ports, source, and templates agree—NetFlow isn’t magic if the UDP reports never land.
Full Explanation
City hall enabling Flexible NetFlow while the collector shows no new flows points first to exporter and collector reachability and matching export parameters so flow packets actually arrive. If the exporter cannot reach the collector—or if destination, source interface, port/protocol, or template/record expectations disagree—caches may build locally while the collector stays empty. Municipal NOC troubleshooting should validate the export path and configuration consistency before redesigning records or blaming unrelated campus features.
Whether HSRP preempt is enabled on the collector’s default gateway fails as the primary focus because FHRP preempt state is not the usual root cause checklist item for missing NetFlow delivery. Whether IGMP version mismatches exist on the collector VLAN fails because IGMP versions govern multicast membership signaling, not NetFlow export success. Whether static NAT is translating the collector’s NTP stratum field fails because that mixes NAT and NTP concepts that do not explain empty NetFlow collectors.
Exam caveat: no flows at collector → check reachability, export destination/source, UDP/TCP port, VRF, ACLs, and template alignment. Local cache presence with zero collector data strongly suggests export-path or parameter mismatch rather than “NetFlow is off” in every case.
Operational check: ping/traceroute from exporter source to collector, verify exporter config and counters, capture export packets if needed, align template versions, and confirm new flows appear after a controlled test conversation through city hall.