Thanks to new directory software, Windows Vista, the successor to the aging Windows XP, could put a greater load on internet servers. But experts disagree over whether we’re headed for a prime-time traffic jam or insignificant slowdown.

Microsoft’s launch of Windows Vista could slow down or stall traffic on the net, said Paul Mockapetris, who is widely credited with inventing the Internet’s Domain Name System (DNS). Mockapetris believes Vista’s introduction will cause a surge in DNS traffic because the operating system supports two versions of the Internet Protocol, a technology standard used to send information over computer networks.

"If you adopt Vista, your DNS traffic is going to double," Mockapetris said in an interview. With many DNS servers already running close to capacity, this can have serious consequences, he said. "You’re going to see brownouts. All of a sudden, it is going to be mud season on the Internet, where things will just be kind of slow and gooey."

Vista may cause an increase in DNS traffic, but not to the extent predicted by Mockapetris, Microsoft countered in a statement provided to CNET News.com last week. Other experts support Microsoft and suggest Mockapetris’ predictions are related to his role at Nominum, the Redwood City, Calif., vendor of DNS products where he is chief scientist.

Others agree that Vista could cause a spike in DNS traffic. But they’re not expecting dire consequences. "Vista, due to its support for IPv6, will cause somewhat higher load on name servers as it checks to see which protocol to use," said Dan Kaminsky, an independent researcher. "But this is not the stuff that blackouts are made of."