In a report published on 4 December, root server operators announced that "on November 30, 2015 and December 1, 2015, over two separate intervals, several of the Internet Domain Name System's root name servers received a high rate of queries." While the report mentions that it is not unusual for root name servers to see anomalous traffic, it also noted that this particular event was "large, noticeable via external monitoring systems, and fairly unique in nature". As a consequence of the incident, some root name servers faced timeouts for valid, normal queries. Nevertheless, several other servers continued to operate under normal conditions.The report ends with underlining that "the DNS root name server system functioned as designed, demonstrating overall robustness in the face of large-scale traffic floods observed at numerous DNS root name servers." More details can also be found in this article from The Register.