Learning from the Flatcar DNS Outage – A Post-Mortem

On February 2nd and 3rd, 2025, Flatcar experienced a significant DNS outage that affected our update and release servers, as well as parts of our CI/CD infrastructure. As a result, users were unable to download new Flatcar releases, retrieve Flatcar images for several hours. The root cause was a miscommunication during a domain transfer, which led to DNS mis-configurations. In collaboration with t