ICANN is accepting applications for new generic top-level domains, which raises an interesting hypothetical: what would happen if someone applied to operate .onion as a normal public DNS domain? Would the application be rejected because .onion is already associated with Tor hidden services? If it were approved, could the same domain name exist in both the regular internet DNS system and the Tor network? How would the Tor Browser choose between a clearnet site and an onion service, and what other technical or security consequences might result?
4 Answers
For most of the internet, very little would change. The main issue would be confusion and possible collisions between public DNS records and existing onion services. Someone using a regular browser might reach a clearnet site, while Tor-aware software would likely continue looking for an onion service, so the two versions could coexist but would not automatically be treated as one website.
If .onion somehow became a normal DNS extension, Tor would still recognize onion addresses using its own protocol. The browser would not simply let ordinary DNS decide where those names go; it would continue routing recognized onion addresses through Tor. Regular browsers and DNS resolvers would treat the name as a normal domain only if an actual public registration and DNS records existed.
A public .onion domain could also create security risks. People might register lookalike names or deliberately host pages that imitate onion services, catching users who copy an address into the wrong browser. Browser behavior around onion links could potentially reveal that a visitor is using Tor, although that capability is not necessarily a secret by itself.
The application would almost certainly be rejected. .onion is reserved as a special-use domain for Tor services, so it is not treated like an ordinary DNS extension. Even without that reservation, the Tor and DNS naming systems are separate, so the same name could theoretically exist in both systems without a direct conflict—similar to identical addresses in different countries.
A similar question comes up with names such as .lan. They are widely used on private networks, even though they may not have the same formal reservation status, so approving them publicly could still create compatibility problems.