public DNS server

• Google (Unfiltered)
  • 8.8.4.4
  • 8.8.8.8
• Global Cyber Alliance (Filters malicious content)
  • 9.9.9.9
• Cloudflare
  • 1.0.0.1
  • 1.1.1.1
• Level 3 Communications
  • 4.2.2.1
  • 4.2.2.2
  • 4.2.2.3
  • 4.2.2.4
  • 4.2.2.5
  • 4.2.2.6

This is a list of public DNS server
Courtesy: http://radoff.com/blog/2009/12/07/google-dns-benchmarking-and-rationale/