DNS over HTTPS (DoH) is a protocol primarily used to increase user privacy and security. A remote DNS query is performed through HTTPS. DoH also increase performance of the resolutions and connections.
Domain Name Service (DNS) is one of the most critical protocols for the Internet because almost everything you do online starts first with a DNS request. And traditionally DNS requests are sent over through UDP and TCP protocols albeit unsecured.
So immediately you begin to resolve from one device point to another the all host of network dependent applications also begin to work. That is how important DNS is.
Now DNS is just a clear text communication sent unsecured especially the recursive responses to the clients are the most vulnerable so is prone to manipulation. Windows admins know what results from a few changes to the host file or the network administrator manipulating the quest traffic to the hotel servers.
Or even worse a maliciously intent individual who takes over a public Hotspot or WiFi will be a master of so many things.
Google and Mozilla Foundation are in the front testing this protocol. And here are the resolvers for those implementing the DoH.
Troubleshooting New Protocol DNS Over HTTPS
DoH is still very new dating back to 2018 with Google and Mozilla testing the protocol. But here are 4 public available and free resolvers you can use:
https://mozilla.cloudflare-dns.com/dns-query (unfiltered by CloudFlare)
https://dns.google.com/experimental (unfiltered by Google. This is the most stable and running for longer)
https://doh.cleanbrowsing.org/doh/family-filter/ (filtered by CleanBrowsing, blocks adult content)
https://doh.cleanbrowsing.org/doh/secure-filter/ (filtered. Blocks malicious domains only)