This paper outlines a Distributed Denial of Service (DDoS) attack which abuses open recursive Domain Name System (DNS) name servers using spoofed UDP packets. Our study is based on packet captures and logs from attacks reported to have a volume of 2.8Gbps. We study this data in order to further understand the basics of the reported recursive name server amplification attacks which are also known as DNS amplification or DNS reflector attacks. One of the networks under attack, Sharktech, indicated some attacks have reached as high as 10Gbps and used as many as 140,000 exploited name servers. In addition to the increase in the response packet size, the large UDP packets create IP protocol fragments. Several other responses also contribute to the overall effectiveness of these attacks.

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