Now we know.  

The Ninth Circuit held today that domain names ending with .com or .net dwell at 487 East Middlefield Road, Mountain View, CA.

The case involved efforts to collect a judgment against a man, John Zuccarini, who owned some .com or .net domain names.  The "situs" of the names mattered for constitutional and state law reasons.

Noting that the case involved a question of type two quasi in rem jurisdiction, the court located the situs as the headquarters of the "registry", VeriSign.  Which made the Northern District of California's appointment of a receiver to grab the domain names just fine.  Office Depot Inc. v. Zuccarini, No. 07-16788 (9th Cir. Feb. 26, 2010).

Registrars register domain names for registrants on registries.  

Sally sells sea shells by the sea shore.