A distributed denial-of-service (DDoS) attack is an endeavour towards bringing a network resource(server) down so that users can't visit a particular site. DDoS attacks are carried out to target a host and interfere or pause (sometimes stop) its services. Generally, two or more persons, or bots send the DDoS attacks. On an average, more than 27 attacks are performed every hour in 2014. As the popularity of these attacks is growing day by day, many attackers are coming in and the cost to doing such attacks is quite low. It does not require any super hardwares or softwares so even low-level hackers are often caught in such attacks.