Will Vista stall Net traffic?

Expert predicts Vista could overflow the Net's infrastructure, causing "rolling blackouts." Some call the forecast "FUD."

Thanks to new directory software, Windows Vista 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.

"It is going to be mud season on the Internet, where things will just be kind of slow and gooey."
--Paul Mockapetris,
DNS inventor

"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."

Vista is the first Windows version to support the new IP version 6, which is designed to provide a broader range of IP addresses. As current IPv4 addresses are becoming scarce, IPv6 will provide easier connectivity across the Internet and remove the need for IPv4-addressing schemes such as network address translation, which can require additional management burdens and cause application incompatibilities.

But IPv6 is far from being universally used. So, Vista will also support the current IPv4. The side effect, according to Mockapetris, is that a Vista PC will make two DNS requests, one for each IP version, instead of just one.

"It is going to try a DNS lookup for the IPv6 address and then a DNS lookup for the IPv4 address," Mockapetris said. "It just uses more DNS, and until we increase the supply, things are going to go slower."

DNS is crucial to the Internet. It functions as a phone book, mapping text-based addresses such as www.cnet.com to the actual numeric IP address. DNS servers are typically run by Internet service providers, hosting companies and larger businesses that have Net connectivity.

Nominum commissioned a survey of the DNS servers run by large broadband ISPs. "It looks like they are right at the knee and curve and if Vista was all of a sudden deployed everywhere, we'd be having rolling blackouts," Mockapetris said. "For my home network, it is not going to matter, but for these people with millions of users, it is going to matter."

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