Deep Inside a DNS Amplification DDoS Attack

A few weeks ago I wrote about DNS Amplification Attacks. These attacks are some of the largest, as measured by the number of Gigabits per second (Gbps), that we see directed toward our network. For the last three weeks, one persistent attacker has been sending at least 20Gbps twenty-four hours a day as an attack against one of our customers. That size of an attack is enough to cripple even a large