quad9: Internet Security & Privacy In a Few Easy Steps
Quad9, a Public DNS Resolver - with Security
https://labs.ripe.net/Members/stephane_bortzmeyer/quad9-a-public-dns-resolver-with-security
Privacy: Using DNS-over-TLS with the Quad9 DNS Service
https://medium.com/nlnetlabs/privacy-using-dns-over-tls-with-the-new-quad9-dns-service-1ff2d2b687c5
1.1.1.1: by cloudflare
https://developers.cloudflare.com/1.1.1.1/
OpenNIC
Pi-hole®: A black hole for Internet advertisements
Securing DNS across all of my devices with Pi-Hole + DNS-over-HTTPS + 1.1.1.1
https://scotthelme.co.uk/securing-dns-across-all-of-my-devices-with-pihole-dns-over-https-1-1-1-1/
How to implement DNS-Over-HTTPS on PiHole, Ubiquiti USG and dnsmasq devices
https://bendews.com/posts/implement-dns-over-https/
Configure Pi-Hole with DNS Over HTTPS
https://oliverhough.cloud/blog/configure-pihole-with-dns-over-https/