Could ICANN actually shut down the whole internet?

Not the whole internet. ICANN coordinates parts of the domain name system, including policy for the top-level domains in the public root. That system helps turn names like example.com into addresses. It does not control the cables, routers, or the basic ability of networks to exchange traffic.

A severe disruption to the root could make many domain names harder to resolve, so websites and services would fail for lots of people. But connections by IP address, private networks, and names already stored in caches could continue working. That would be a major DNS crisis, not an instant shutdown of all internet connectivity.

The claim that ICANN can simply revoke every top-level domain with one switch is too strong. ICANN coordinates root-zone changes, but the root service is distributed across independently operated servers, and updates involve more than one organization. ICANN does not own all of those servers or unilaterally control every resolver.

If the root were badly disrupted, recovery would depend on operators and network providers agreeing on what to serve next. DNS data is cached at many layers, which could soften the immediate impact, but caches expire. Replacing the root system is not necessarily a quick or clean fix, since different groups would need to adopt compatible data and trust the replacement.

For an individual country, there is no simple ICANN switch that turns off internet access there. A country’s connectivity depends on its providers and international links, while domain names depend on registries, DNS operators, and local resolvers. Different actors could disrupt parts of that picture, but it would not be the same as ICANN switching off the country’s internet.

People can run alternative naming systems, but that does not automatically create one seamless replacement. If different systems give the same name different answers, users and services can end up split across incompatible versions of the internet. More decentralized options are possible, though they still need broad coordination to be useful to everyone.

Even if ICANN stopped doing its job, the internet would not vanish. The harder problem would be keeping names unique and maintaining a shared set of records. Networks could keep exchanging data, but people would have more trouble reaching services by familiar domain names, and different groups might create conflicting replacements.