Three vectors were exploited in the recent DDoS attack against Spamhaus: 1) Amplification of DNS queries through the use of DNSSEC signed data; 2) Spoofed source addresses due to lack of ingress filtering (BCP-38) on originating networks; 3) Utilisation of multiple open DNS resolvers While. 1) is unavoidable simply due to the additional data that DNSSEC produces, and 2) "should" be practised as part of any provider's network configuration, it is 3) that requires "you and I" ensure that systems are adequately configured. more