How the Dyn outage affected Cloudflare

On October 27, 2016, popular DNS service Dyn suffered three waves of DDoS attacks that affected users worldwide, including some Cloudflare customers. The Domain Name System (DNS) is responsible for converting human-readable domain names to IP addresses for websites. During the Dyn outage, Cloudflare's internal DNS query error rate spiked in two periods. China was largely unaffected due to different caching configurations within its data centers. In response to the incident, Cloudflare is making changes to its internal DNS infrastructure to improve performance during major provider issues or outages. The company is also testing and rolling out a 'serve stale while revalidating' feature to mitigate the impact of similar events for customers using CNAME records from third-party providers.