A study conducted by a team of researchers at the University of Carolina San Diego, Saarland University, and University of Twente has revealed thatone third of all IPv4 address space estimated to be in use have been affected by at least one denial-of-service (DoS) attack over the past two years. The researchers based their study on data from four global Internet measurement sources: backscatter traffic to a large network telescope; logs from amplification honeypots; a Domain Name System (DNS) measurement platform covering 60% of the current namespace; and a DNS-based data set focusing on DDoS Protection Services (DPS) adoption. Other main findings of the report: often targets are simultaneously hit by different types of attack; web servers were the most prominent DoS attack target; and an average of 3% of domain names registered in .com, .net, and .org were involved in DoS attacks daily; the most commonly targeted countries were the USA, China, Russia, France, and Germany.