In this paper, the authors study the characteristics of DDOS attack, various models involved in attacks and to provide alternative. To defenses mechanism with their improvements to combat DDOs attack. Recent DDOS attack has demonstrated horrible destructive power by paralyzing web servers within short time. DDOs detection method based on Hadoop that implements an HTTP get flooding detection algorithm in MapReduce on the distributed computing platform. An assort on a network that floods it will so many requests that regular traffic is either solved or completely interrupted.