Why Your DNS Failover Didn't Actually Fail Over

The failover was declared at 02:14. The runbook was followed. DNS records updated. Health checks passing on secondary. The on-call engineer closed the incident bridge call at 02:31 with a single line in the ticket: failover complete . At 02:32, a monitoring alert fired. Traffic was still hitting the dead primary. The DNS record had changed in seconds. The traffic moved 18 minutes later. Only one of those numbers mattered. This is dns failover testing failure in its most common form — not a misco