In today’s world, IT system's users need quick access to information from every part of the network. Distributed Denial of Service attacks (DDoS) has become a problem as they create network unavailability by blocking the services via seizing system resources in a computer in the network until they stop functioning. Hence having DDos prevention is a must.

In such situations, a user is working on the system loses the connection and is stuck in the middle of the work. The user is not able to log out of the system which user usually do when there is a loss of connection or connection is timed out. DDOS attack creates big trouble for IT systems and they should be eliminated. (QOS) Quality of service can be one method which can work on all routers in the network. Cloud DDoS protection is launched to make the system and networks resources unavailable for the users so that nobody can access it. Web servers, default gateways, personal computers are mostly targeted in these attacks. Most of the hackers have their aim to explore a way through and grab the secret information which is compromised confidentially. DDOS attacks are a weapon of choice for hackers and Cyber criminals as it is inexpensive to execute, and difficult to stop and impact a very large network of users.

Many organization are struck by DDOS and Cloud Computing and are left to scramble in an effort to stop the attack once the attack is started. Sometimes coordination with ISP may require that provides network access. This is especially true when an ISP is forced to "null route" a victim to Protect Cloud from DDOS – meaning that to protect other customers, the ISP routes traffic intended for the victim into the trash. This of course effectively prevents all access, including from legitimate users. Over the past few years, DDoS security setup has become even more challenging as Cyber-attacks have grown not only in scale but in sophistication, bypassing traditional firewalls and taking advantage of vulnerabilities in web applications. DDOS attack vectors have shifted from the network and transport layers to the application layer as Cyber criminals take advantage of layer 7 protocols for amplification purposes. As a result, hackers are able to generate large-scale attacks with fewer machines and fewer connections—connections that appear to be used legitimately—making this method of attack both efficient and stealthy.