8.8.8.8
or 1.1.1.1
do when they don't have a result in their cache.
There are 13 root nameservers (this list comes from here):
{{rootServers.join(", ")}}
Let's pick one at random: {{rootNS}}
FAQ:
How can I get the same information from a command line tool?
Use dig +trace yourdomain.com
Where are the DNS queries being made?
It's a combination of this little Go program and this Javascript code