The deadly attacks of September 11 didn't just give us tighter airport checkpoints, new wiretapping and surveillance laws, and countless metric tons of explosives air-lifted to Afghanistan.

They also prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to toss out its customary agenda and replace it with a three-day special meeting, which begins Tuesday, on how to guard the Net's most vulnerable portions from terrorist attacks. In the words of an ICANN announcement from September, the "overriding imperative" is to figure out how to thwart al-Qaida or its domestic relations from wreaking electronic havoc on the Internet's domain name system, which translates names like wired.com to the numeric address 209.202.221.20. Much of the Internet's infrastructure -- such as e-mail servers and websites -- is decentralized and not easily targeted by malcontents. But since the domain-name system intentionally was designed with one master database for efficiency's sake, it also represents a centralized point of failure. Currently there are 13 computers, called root servers, that manage global Internet traffic. Some can be found in high-security buildings such as Verisign's Herndon, Virginia, offices -- home to the master "A" root server. Others are run by volunteers at universities and corporations in Tokyo, Stockholm and London. Concern over root-server security led to an Internet Engineering Task Force best-practices memo last year, which stressed that physical and electronic security must be paramount. A malcontent who breached a root server could spoof domain names, forge websites and disrupt the Internet for millions of people.