Abstract: While cloud computing provides various benefits to users, there are also underlying security and privacy risks such as multi-tenancy, resource pooling and shareability features can be exploited by cybercriminals and anyone with a malicious intent. Distributed Denial of Service (DDoS) attacks are considered the main methods to destroy the availability of critical online services they overwhelm the victim with huge volume of traffic and render it incapable of performing normal communication or crashes it completely. This flooding attacks due to that all network resources and operations are blocked all at once. This study discuss some related approaches for mitigating or preventing DDoS attacks for cloud environment. It also presents a conceptual cloud DDoS defense framework based on classifier and change point detection components to compare the traffic and resource usage in normal and attack situations and take a countermeasure action to drop threated packet and alarm administrator.