If you've been doing some last-minute Amazon holiday shopping on Wednesday evening, you've probably noticed that Amazon's website was sluggish and, at times, completely down. The same fate greeted Wal-Mart, Expedia and a number of smaller sites. The reason? A severe DDoS (Distributed Denial of Service) attack on the servers of Neustar, the company that offers DNS services to many major companies under the name UltraDNS.
The attack that started at 4:45 p.m. PST and lasted for about an hour, but it was quite severe, especially because it also affected Amazon's S3 and EC2 services (upon which many other web services rely), as tweeted by Amazon's lead Web Evangelist, Jeff Barr. Currently, Amazon's Service Health Dashboard shows that their services are working normally.