Given the extraordinary and rapid changes in the DDoS terrain, traditional DDoS mitigation tactics such as bandwidth overprovisioning, firewalls, and intrusion prevention system (IPS) devices are no longer sufficient to protect an organization’s networks, applications, and services. Verisign has successfully defended its global DNS infrastructure against DDoS and other attacks for more than 12 years and has maintained 99.99 percent availability of its critical infrastructure during that time.