Not all DNS records are Pulled - Cloudflare Community
2019/05/26 ... Records created on Cloudflare generally propagate Globally in under 30 seconds. It is likely a caching issue with the DNS server you have ...
https://community.cloudflare.com/t/not-all-dns-records-are-pulled/86107Secondary DNS - Deep Dive - The Cloudflare Blog
2020/09/15 ... Secondary DNS involves the unidirectional transfer of DNS zones from the primary to the Secondary DNS server(s). One primary can have any number ...
https://blog.cloudflare.com/secondary-dns-deep-dive/