He argues that the city had, and still has, an opportunity to protect the .nyc domain name so that small businesses are not put at a disadvantage. One way, he said, would be to follow the approach used in London, where businesses had to submit evidence that they had been operating under the name they were trying to register.

“Without that, they’re catering to squatters,” Mr. Lowenhaupt said.

Ah, cybersquatting. A man in Minneola, Fla., who had nothing to do with the band Jethro Tull, but registered JethroTull.com, offered to sell it to the band for $13,000; at various points since the late 1990s, a website called WhiteHouse.com was used for pornography and real estate links, which people and children often stumbled on when they were meaning to go to WhiteHouse.gov. Forbes reported that in January, when a new domain called .clothing opened, “nobodies scattered around the globe” registered the names of brands like Adidas, Tommy Hilfiger, Aéropostale and Burberry.

Who, or what, is in charge?

Globally, the domain name system is regulated by the Internet Corporation for Assigned Names and Numbers, but other companies do the actual registration of sites.

Under Mayor Michael R. Bloomberg, the city signed a contract with a registry called Neustar to administer the .nyc domain. Neustar will conduct auctions when more than one party tries to sign up for the same name. The city gets 40 percent of the revenue.

New York has also reserved 2,000 premium names — the list is not yet public — but has announced that it held onto neighborhood names. That means, for instance, ParkSlope.nyc. cannot be bought on the market.

“That was a positive step that the de Blasio administration took,” Mr. Lowenhaupt said.

Still, he added, “They are catering to a crowd around the world that is going to buy these names and sell them back to us at inflated prices.”

The city says the registry will be policed to make sure that each person or business is actually located in New York City, and not using some subterfuge.