You are sort of correct. NTP is pretty decentralized. DNS has a few specific servers (root servers) that all DNS eventually hits to find where to get a result,

You are sort of correct. NTP is pretty decentralized. DNS has a few specific servers (root servers) that all DNS eventually hits to find where to get a result, but, the 'tree' of DNS resolution is much different from that of NTP, which doesnt have such a tree, except as defined by any DNS entries, if they are used (ex pool.ntp.org has many A records for many ips or CNAMEs to other domains (ex 0.pool.ntp.org)). There are many contributors to the official timekeeping. Most facilities who do science will have their own actual atomic clock, which they then share out the data, in the form of an NTP server, however, they will not typically use data from the rest of the world, except for correlation events. The rest of the world relies on a handful of clocks which are either from NIST (ntp.org I think is owned by them), or from major providers like cloudflare (not sure they have an ntp server available the public can use, im almost certain that they would use their own atomic clock internally for security reasons), microsoft also has one, i think, afaik they would need to because they provide their own ntp pool, but they may just aggregate from multiple NIST servers. You can setup your own NTP server as well, and setup systems you own to start using it instead of whatever is configured. And, if one were so inclined, could even find and run your own atomic clock, and register it with the ntp pool. Im actually not sure the atomic clock is required, id hope it would be, but idk.