It's well done, helpful especially for non-technical folks or beginners. But I'm annoyed with using the dnssimple.com as example site along with name servers at ns1.dnssimple.com . So, a newbie may wrongfully assume that example.com may have name servers like ns1.example.com which is not the case. May sound silly, but any one totally new to the DNS could easily misunderstand it. They could have used example.com to avoid any ambiguity.
Entertaining irony; I couldn’t resolve the A record for that domain from my pi-hole and nearly wrote an embarrassing comment here before I checked another resolver. All sorted now though