A public recursive name server (also called public DNS resolver) is a name server service that networked computers may use for query to DNS, the decentralized Internet naming system, in place of or in addition to name servers operated by the Internet service provider to which the devices are connected.

Below is a list of public DNS service operators.

Quad9

Quad9 is a not-for-profit public-benefit organization supported by IBM, Packet Clearing House (PCH), Global Cyber Alliance (GCA), and many other cybersecurity organizations for the purpose of operating a privacy-and-security-centric public DNS resolver. Its main differentiators from other DNS resolvers are that it does not record the queries users send to it, and that it automatically blocks domains known to be associated with malicious activity. Quad9 offers DNS over TLS service over port 853, DNS over HTTPS over port 443 and DNSCrypt service over port 443. - Wikipedia

Features

DNS over TLS
DNS over HTTPS
DNSCrypt

IPv4

9.9.9.9 and 149.112.112.112

IPv6

2620:fe::fe and 2620:fe::9

OpenDNS

OpenDNS is a company and service that extends the Domain Name System (DNS) by adding features such as phishing protection and optional content filtering in addition to DNS lookup, if its DNS servers are used. The company hosts a cloud computing security product suite, Umbrella, designed to protect enterprise customers from malware, botnets, phishing, and targeted online attacks. - Wikipedia

Features

DNSCrypt

Standard

IPv4

208.67.222.222 and 208.67.220.220

IPv6

2620:119:35::35 and 2620:119:53::53

FamilyShield

The FamilyShield recursive nameservers block pornography, proxy servers and phishing sites.

IPv4

208.67.222.123 and 208.67.220.123

CloudFlare

1.1.1.1 is a free Domain Name System (DNS) service. The public DNS service and servers are maintained and owned by Cloudflare in partnership with APNIC. The service functions as a recursive name server providing domain name resolution for any host on the Internet. - Wikipedia

Features

DNS over TLS
DNS over HTTPS

IPv4

1.1.1.1 and 1.0.0.1

IPv6

2606:4700:4700::1111 and 2606:4700:4700::1001

Google DNS

Google Public DNS is a free Domain Name System (DNS) service offered to Internet users worldwide by Google. It functions as a recursive name server. - Wikipedia

Features

DNS over TLS
DNS over HTTPS

IPv4

8.8.8.8 and 8.8.4.4

IPv6

2001:4860:4860::8888 and 2001:4860:4860::8844

OpenNIC

OpenNIC is a user-owned and user-controlled top-level Network Information Center that offers a non-national alternative to traditional Top-Level Domain (TLD) registries such as ICANN. - Wikipedia

IPv4

185.121.177.177 and 169.239.202.202

IPv6

2a05:dfc7:5::53 and 2a05:dfc7:5::5353