An example of a site that painted something only for IPv6 users.
An example of a site that painted something only for IPv6 users. - 
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Jeremy Hobson: If you go online today, you may be seeing a whole different web. That's because today Internet companies are taking part in the largest-ever one-day test of a system that will eventually be the Internet's backbone.

Marketplace's Jennifer Collins reports.

Jennifer Collins: We've got so many devices that use the Internet -- smartphones, laptops, tablets -- that we're running out of ways to connect. A next generation system has tons more space, but isn't widely used. It's called Internet Protocol Version 6. The test today sounds even catchier: IPv6 Day.

Martin Levy: Not just IPv6 Day, World IPv6 Day.

Martin Levy is with Internet service provider Hurricane Electric. Today, Google, Yahoo, Facebook and hundreds of others are testing the v6 system. Most users shouldn't notice a problem...

Levy: Unless there is a configuration issue. That's the failure mode that we're looking for.

If that happens, you won't be able to get to the websites of test participants. And that's on purpose. Michael Van Norman is director of network engineering at UCLA.

Michael Van Norman: The reason that the providers have all decided to do this on the same day is so that none of them are disadvantaged by looking like they're broken while their competitors look like everything's fine.

Van Norman says it's important to work out the kinks. UCLA, for one, will be rolling out the system in its dorms this summer.

I'm Jennifer Collins for Marketplace.

You can see if you're connected to IPv6, or have support for it on your computer, by clicking on this link provided by Google.