There is a new kind of denial-of-service attack hitting the Internet these days, and it has VeriSign and others responsible for handling the Internet's infrastructure very worried. The unusually powerful attacks strike at the basic structure of the Net, exploiting the computers that manage online traffic and using them to overwhelm Web sites. <A HREF="http://news.yahoo.com/s/nf/20060320/tc_nf/42201">The new form of attacks</A> emerged at the end of December 2005 and accelerated in January before settling down about mid-February, said VeriSign Chief Security Officer Ken Silva.