"SAN FRANCISCO — Major websites were inaccessible to some East Coast users in the United States Friday morning and to people across the country in the early afternoon after a company that serves as an internet switchboard said it was under attack.
Users reported problems reaching a range of websites, including Twitter, Netflix, Spotify, Airbnb, Reddit, Etsy, SoundCloud and The New York Times.
Dyn, whose servers monitor and reroute internet traffic, said it began experiencing what security experts call a distributed denial-of-service attack just after 7 a.m. The company, based in Manchester, N.H., said it had fended off the assault by 9:30 a.m. But by 11:52 a.m., Dyn said it was again under attack.
A distributed denial-of-service attack, or DDoS, occurs when hackers flood the servers that run a target’s site with internet traffic until it stumbles or collapses under the load. Such attacks are common, but there is evidence they are becoming more powerful, more sophisticated and increasingly aimed at core internet infrastructure providers.
Going after companies like Dyn can cause far more damage than aiming at a single website."
Internet Attack Disrupts Major Websites - The New York Times