A Distributed Denial of Service (DDoS) is an attack on a network which is designed to bring it to a halt. This is done by sending useless traffic to a specific service/port on a server. The amount of traffic sent would overwhelm the service, so that legitimate traffic would be dropped or ignored.

DDoS attacks have developed from the basic DoS attacks that were in the wild in 1997. These attacks originate from one source and can emerge from 100