> The Domain Name System (DNS) is a service used in converting a computer’s host...

> The Domain Name System (DNS) is a service used in converting a computer’s host name or a Top-Level Domain (TLD) into an IP address

Hostnames and TLDs are different concepts in DNS. It is a mistake to conflate them.

TLDs are the top level (rightmost) part of domain names, such as specifically “com” in “example.com”.