CERT.be published a white paper on proactive and reactive measures to combat DDoS attacks, late 2015. A DDoS attack (or distributed denial-of-service attack) attempts to shut down a webserver by overloading it with a huge number of page requests. The server can no longer process this enormous demand, causing the website to be unavailable for a certain time, until the attack stops or is blocked. With this white paper, CERT wants to help anyone wishing to take measures against such an attack. It also contains tips and tricks on how to best respond to such a DDoS attack.