Distributed denial-of-service attacks on root nameservers
Distributed denial-of-service attacks on root nameservers are Internet events in which distributed denial-of-service attacks target one or more of the thirteen Domain Name System root nameserver clusters. The root nameservers are critical infrastructure components of the Internet, mapping domain names to IP addresses and other resource record (RR) data.
Source: Wikipedia — Distributed denial-of-service attacks on root nameservers (CC BY-SA 4.0)