AWS DNS Outage Explained

On October 19, 2025, AWS suffered a massive DNS outage that took over 24 hours to resolve. After ten days, the company released a root cause analysis revealing that a DynamoDB control-plane change inadvertently broke DNS records, which cascaded into widespread EC2 instance failures and issues with Network Load Balancers.

The post breaks down the timeline and technical details: how the DynamoDB mistake led to DNS resolution problems, why EC2 health checks started failing, and how the Network Load Balancers ultimately lost connectivity. A full RCA is available on the AWS site for anyone who wants the nitty-gritty.

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