= DNS

• https://atlas.ripe.net/
• https://tldtest.net/
• https://zonemaster.net/
• https://dnsviz.net/

1.1.1.1  Cloudflare
9.9.9.9  Quad9  https://en.wikipedia.org/wiki/Quad9
8.8.8.8  Google


IPv6 certifications: https://ipv6.he.net/certification/