At its height, the strike on spam-blocker Spamhaus is understood to have involved an attack rate of 300 gigabytes per second, making it the largest DDoS attack ever recorded.
However, there have been reports in recent days of a larger attack against CloudFlare, a global content delivery network firm, that was close to 400 gigabytes per second.
Matthew Prince, CloudFlare's chief executive, tweeted: "Someone's got a big, new cannon. Start of ugly things to come."
Speaking to Sky News in December, Cabinet Office Minister Francis Maude, who is overseeing the strategy to defend the UK's computer systems from attack said that cyber security was a "never-ending battle".
"The need to raise awareness will continue for ever, it will always be a work in progress,"