Yesterday, I got a phone call from one of my friends who is working in Amazon as a software developer. He told me to see Amazon.com in my browser. I followed his instruction. Then I came to know that Amazon was down. I only a blank screen with the error message: “Http/1.1 Service Unavailable. The site went offline for nearly two hours between about 1:30 p.m. and 3:20 p.m.on Friday afternoon. I asked him the reason of this problem in this website. He told me that it is due to some DOS attack. Yeah, it was some distributed denial-of-service (it happened with Amazon in 1999 also) attack that struck the Web site’s load-balancing system. Actually the DDoS attack bypassed AWS services like Amazon’s S3, which ultimately caused big loss for Amazon’s online retail business. After some time, Amazon fought off the attack and the site again became online for its customers. There has been 20 % increase in traffic on Amazon since last year, so the massive amount of connections made the site offline. It ultimately, cost the company loss of $1.8-million.

A denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a computer resource unavailable to its intended users. One common method of attack involves saturating the target machine with external communications requests, such that it can’t respond to legitimate traffic. DoS attacks are implemented by either forcing the targeted computer(s) to reset, or consume its resources (bandwidth) so that it can no longer provide its intended service or obstructing the communication media between the intended users and the victim so that they can no longer communicate adequately. It causes consumption of computational resources, such as bandwidth, disk space, processing time etc.