There are many “platforms” that offer the ability to have your own domain for publishing content even while they handle the backend, hosting, and other sever-related stuff. An example of this is Substack.
Suppose I come across a domain like https://www.lennysnewsletter.com/ (which is hosted by Substack), how do I verify for sure that it is indeed hosted by Substack? Is there an automated, programmatic way to determine this, perhaps using geekflare.com or some other DNS lookup API service? Or any other way?