reference Cloudflare DNS server

rule:
  meta:
    name: reference Cloudflare DNS server
    namespace: communication/dns
    authors:
      - william.ballenthin@mandiant.com
    scopes:
      static: function
      dynamic: thread
    references:
      - https://www.techradar.com/news/best-dns-server
  features:
    - or:
      - string: "1.1.1.1"
      - string: "1.0.0.1"