Cloud computing with its recent development, made it’s accessible by almost everyone. Millions and millions of people daily store their data in the cloud platform and utilize for various kind of need. In this scenario, distributed denial of service (DDoS) attacks is one of the common issues in the day-to-day usage, which severally affects the availability of the resources or services. The challenge is to create a DDoS detection and mitigation system that can protect against both volumetric and application-specific resource starvation and exhaustion attacks. In this paper, a new method named MOTAG has been proposed. This method of moving-target defence to overcome DDoS attacks will repeatedly shuffle the assignments between client to server in order to identify the malicious clients first and then to quarantine them.