Doing some digging about why a specific DNS wasn't propagating properly everywhere, I found out that it was related to a wrong DNSSEC declaration.
- Tool to check if the DNS record is properly propagated https://www.whatsmydns.net
- Debug DNS settings & DNSSEC settings
a bit more details about DNSSEC
https://blog.ovhcloud.com/an-introduction-to-dnssec/
DNS DNSKEY and DS records "The DNSKEY and DS records are used by DNSSEC resolvers to verify the authenticity of DNS records."
https://www.cloudflare.com/learning/dns/dns-records/dnskey-ds-records/
some debuging steps
https://serverfault.com/questions/1018543/dns-not-resolving-in-all-locations-after-a-week
