What you said here is not really on topic, but it is literally part of DNS. I already explained it in my other comment, but here:
DNS, by design, uses authoritative nameservers, which is what cloudflare and quad9 host. These authoritative hosts distribute their records to caches (usually just recursive DNS resolvers) to ease and distribute the load. It’s literally in all of their documentation, and explained in pretty plain english on their pages.
Much of the Quad9 platform is hosted on infrastructure that supports authoritative DNS for approximately one-fifth of the world’s top-level domains, two root nameservers, and which sees billions of requests per day.
When a record is updated in your domain (or cloud) provider, it is distributed via an authoritative nameserver hosted by that company. These get distributed to the root name servers, which then distribute the records to other authoritative nameservers.