DDoS's make up 2% of all traffic in the tubes.

One out of every 50 packets on the internet is malicious junk intended simply to clog the tubes, according to a high level traffic analysis by Arbor Networks.

Distributed Denial of Service attacks or DDoSes aim to bring a site down by bombarding it with fake requests for a web page or image. It's like having 1,000 people continually crank calling a company -- the real customers can't get through.

Arbor now says those attacks account for about two percent of internet traffic, with peaks of up to five percent.

Some DDoSes are spurred by online grudges, such as the ones that occasionally target the anti-phishing site CastleCops or the large one launched against Estonian targets by Russian nationalists last year. Others are launched by cyber-criminals as part of an extortion attempt against an online retailer.

Plagerised from: Threat Level.