On 28 Feb 2019, at 11:53, Mike Marynowski wrote:
There are many ways to determine what the root domain is. One way is
analyzing the DNS response from the query to realize it's actually a
root domain, or you can just grab the ICANN TLD list and use that to
make a determination.
What I'm probably going to do now that I'm building this as a cached
DNS service is just walk up the subdomains until I hit the root domain
and if any of them have a website then it's fine.
This is more complicated than it seems. I have the t-shirt to prove it.
I suggest you look at the Mozilla Public Suffix List at
https://publicsuffix.org/ — it was created for different purposes,
but I believe it maps well enough to my understanding of your use case.
You'll be able to pad the gaps using a custom list.
Best regards
-lem
