Welcome to the DNS Health Viewer! Please see GitHub for what this is & how to contribute.
In short, these are the top-1000 domains from the 'Majestic Million' as resolved by the Teaching Resolver from the Hello DNS DNS educational project. Unlike production resolvers, 'tres' is not tolerant of misbehaving authoritatives or bad configurations. If 'tres' can resolve your domain, this is a pretty good sign.
Click on the name of a domain for a textual output of the resolution process. Click on the 'numqueries' number to get a Graphviz plot.