We now know why the DNS failed

On October 19, 2025, AWS suffered a more-than-24-hour outage when a DNS mishap in Dynamo brought down EC2 and Network Load Balancer services. Ten days later, AWS published a detailed root-cause analysis pinpointing the exact chain of errors that took the DNS offline.

The deep dive covers how Dynamo’s DNS went dark, followed by cascading EC2 and NLB failures. You can read the full RCA on AWS’s website for all the nitty-gritty.

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