Distributed denial of service (DDoS) attacks are considered the most common and often the most destructive among all threats to network infrastructure. For the last decade the number of DDoS attacks constantly grows. They become more elaborate and sophisticated making standard security techniques went out of date quickly. In the review we collected, investigated and link together data from academic publications and information security reports provided by top companies in the field. We marked out tendencies in evolution of DDoS attacks, characterized protection systems, and summarized the last achievements and future developments in application of intellectual methods for network security.