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UltraDNS Outage Causes Multiple Website Failures

This morning, our DynECT Platform monitoring system noticed a problem, a big one. From our global perspective, it appears that many online services, including (the store, AWS, and S3),,, and, had some serious DNS troubles. As many of our readers know, DNS is the glue that binds domain names, like to their respective server’s IP addresses ( Without DNS, nothing works; no web, e-mail, voip, IM, file sharing, etc.

The DynECT Team quickly began to analyze the situation by checking the resolution chains for these popular web sites. Our analysis revealed that multiple UltraDNS PDNS (a special class of ultradns server) nodes were failing to respond to all DNS queries. clearly knew about the problem, as our monitoring then detected a change in the delegation for from UltraDNS’ PDNS nodes to their UDNS nodes at approximately 8:50 am Eastern.

We continued our analysis by checking our global performance trending system – some graphs showing the problems are below.

DNS Outage Affecting Domains 2

You can see more graphs from our monitoring on our flickr photostream.

We speculate that the source of the problem may have been a large scale Denial of Service attack against UltraDNS, or an internal operations problem. When we were able to sucessfully query UltraDNS servers, responses were slow to come back, or largely timed out. The problem began to clear itself up around 10:00 am Eastern, when we saw DNS responses returning quickly again, and our favorite sites coming back online.

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Whois: Tom Daly

Tom Daly is a co-founder of Dyn, a pioneer in managed DNS and a leader in cloud-based infrastructure that connects users with digital content and experiences across a global internet.

To current Dyn Customers and visitors considering our Dynamic DNS product: Oracle acquired Dyn and its subsidiaries in November 2016. After June 29th, 2020, visitors to will be redirected here where you can still access your current Dyn service and purchase or start a trial of Dynamic DNS. Support for your service will continue to be available at its current site here. Sincerely, Oracle Dyn