Show HN: Identifying the DNS server used to fulfill a HTTP request

Nope. See the second footnote at the end of the blog post. I just couldn't get the right mix of search terms to bubble up the relevant sites (like the one in your comment!) If it wasn't a hit on a web-interface to nslookup it was a hit about showing your local DNS settings on Windows or Mac.

I get the feeling that there are many incarnations of this same tool being re-invented every so often. What would you use to search for something like this?