OpenDNS

https://www.opendns.com/

IPv4 DNS Server:

208.67.222.222

208.67.220.220

IPv6 DNS Server:

2620:0:ccc::2

2620:0:ccd::2

OpenDNS also offers DNS servers that block adult content, called OpenDNS Family Shield. Those DNS servers are 208.67.222.123 and 208.67.220.123. A premium DNS offering is also available, called OpenDNS Home Internet Security. See more in the OpenDNS Knowledge Base.