Cloudfare DNS service

Cloudfare has some DNS server addresses that block malware and/or adult content. 

Cloudflare DNS, no blocking:

• Primary DNS: 1.1.1.1
• Secondary DNS: 1.0.0.1

Cloudflare DNS, blocking malware only:

• Primary DNS: 1.1.1.2
• Secondary DNS: 1.0.0.2

Cloudflare DNS, blocking malware and adult content:

• Primary DNS: 1.1.1.3
• Secondary DNS: 1.0.0.3

https://blog.cloudflare.com/introducing-1-1-1-1-for-families/