"The assertion of this injunction is, in essence, that if there is any technical possibility of denying access to content by a specific party or mechanism, then it is required by law that blocking take place on demand, regardless of the cost or likelihood of success."<p>Technically, this block does not stop anyone from getting the IP address for a domain. Anyone can resolve a domain name using public information that is disseminated from domain name registries, domain name registrars and other authoritative DNS providers. Quad9 is just a third party DNS provider, not an authoritative source for IP addresses. In theory, third party DNS providers could refuse to provide (resolve) the IP address for any domain name. They could do this on their own accord, to suit their own interests, or at the behest of anyone, e.g., an end user, a financial contributor (donor), an interested corporate partner, or perhaps pursuant to a court-ordered injunction.<p>In fact, this in exactly what Quad9 does: they block domains. They advertise this capability on their website, where even the most non-techical reader could find it. From the "About" page:<p>"Quad9 blocks against known malicious domains, preventing your computers and IoT devices from connecting to malware or phishing sites."<p>Third party DNS has a number of potential problems; filtering is one. Funny how people have literaly turned that problem into a selling point. For example, OpenDNS, now part of Cisco, started a business doing DNS-based filtering.<p>Personally I fail to see why third party DNS (ISP-provided DNS or so-called "open resolvers") remains a preferred method of retrieving IP addresses or other RRs. IMO, there is no technical advantange anymore.<p>Many years ago I wrote a system for resolving domains without using recursion, using only authoritative queries, never setting the RD bit. It was very fast. Faster than a cold cache, IME. It could actually get faster as it acquires more addresses of authoritative servers, because it does not need to look them up again. It "learns". The best aspect though is that there are no unecessary third party middlemen. Third party DNS providers are not authoritative sources for any RR. They are middlemen. They do not operate for free. They are potentially subject to influence from whomever pays the bills.<p>People often discuss "privacy" when they discuss third party DNS service. IMO, using a shared third party DNS cache seems antithetical to "privacy" (not to mention "security"). In any event, it enables filtering by someone who is not an authority for the DNS data they are serving, a middleman. This is the view of an end user, not a corporation nor a developer working for one.