A widespread electronic attack on a company that handles traffic for some of the world's most-visited Web sites <A HREF="http://news.yahoo.com/news?tmpl=story&u=/washpost/20040615/tc_washpost/a43635_2004jun15">knocked several high-profile sites offline</A> for at least 45 minutes early Tuesday. The attack targeted Internet servers run by Cambridge, Mass.-based Akamai Technologies, which distributes and manages Web data for companies such as Microsoft, Yahoo, Federal Express and Xerox.