Editor’s note: The full report titled Mandated DNS Blocking: A Guide for Legal Professionals was published on 30 March 2026. You can read the Executive Summary below and continue reading the full report in the PDF format. The short version titled Mandated DNS Blocking: Critical Considerations was published on 7 November 2025. Both versions are also available in the side menu.
Executive Summary
The Domain Name System (DNS) provides a critical function for the Internet. It enables people to use familiar words, like “example.com”, instead of long numerical addresses to reach websites, send emails, and use online services. Without this naming layer, the Internet would not be the practical, global communications system the world depends on today.
Because the DNS offers this function, it is sometimes treated as a convenient point of enforcing public policy, especially since voluntary or parental DNS filtering is a common practice. Governments and courts increasingly turn to mandated DNS blocking to stop access to certain content, whether to combat child exploitation, copyright infringement, restrict online gambling, or address politically sensitive or unlawful material.
The message of this report is simple: Mandated DNS blocking may look like a straightforward technical fix to enforce public policy, but in practice, it is blunt, costly, and even counterproductive. Understanding why requires viewing the DNS as a shared global infrastructure and recognizing the impact when it is tasked with a job it was not designed for.
Why DNS Blocking Is a Blunt Tool
DNS resolution only translates a domain name to the IP address of a web server, not the full path of a resource. For example, when a user enters “https://example.com/page1” in their web browser, the DNS only resolves the “example.com” part to an IP address. The rest of the path, i.e., the “/page1” part (or any specific image, video, or file), is handled once a connection has been established with the web server. This means DNS blocking can only apply to entire domain names, not to individual pages or files.
DNS Blocking Breaks Things
If a single page under a domain is unlawful, blocking at the DNS level prevents access to all the other, lawful material hosted under the same domain. The impact can be particularly significant for shared platforms such as social networks, blogging services, or cloud services, where millions of distinct users might rely on the same domain name. A single block can therefore disrupt vast amounts of unrelated content and services. This includes important implications for security, as DNS blocking orders hinder the widespread adoption of Domain Name System Security Extensions (DNSSEC).
DNS Blocking Is Easy to Circumvent and Ineffective
Determined users have many easily accessible (and even automated) circumvention techniques to avoid DNS blocking. This drastically reduces the long-term effectiveness of DNS blocking.
Furthermore, DNS blocking only prevents a resolver from translating a blocked domain name into its corresponding IP address. It does not remove the underlying content from the Internet. In practice, the material usually remains available and can be accessed again once it is tied to a new domain name.
DNS Blocking Has Effects Across Geographies and Jurisdictions
Policies for blocking content can affect users far beyond the intended jurisdiction unless the operator can reliably and very quickly (within milliseconds) distinguish users’ locations. However, this is complicated by the limitations of IP-based geolocation, which can result in lawful users outside the intended jurisdiction being denied access, while targeted users may still be able to access it.
Furthermore, because the DNS is a global system, blocking measures often collide with other national legal frameworks. What may be prohibited in one jurisdiction may be legal in another, and a blocking order issued domestically cannot easily be reconciled with such differences. The operator could then face a legal dilemma: comply with the order and risk violating the rights of users or laws of another jurisdiction, or refuse and face penalties in the jurisdiction imposing the block.
DNS Blocking Comes at a Cost
Implementing DNS blocking can be costly for both operators and users. Implementing the block, particularly when applied selectively by jurisdiction, requires not only technical changes to resolver infrastructure but also ongoing operational investment. The more fragmented the rules become, the greater the operational burden on DNS operators and the greater chance of error in over- or under-blocking. From a user’s perspective, blocking also risks affecting service quality as integrating geolocation and blocklist checks into DNS resolution increases latency. Although delays of just a few milliseconds may seem negligible, at the scale of the Internet, they can have a significant impact on user experience as complex pages load much slower as each component is reached via DNS and undergoes a blocklist check. This can also cause users to switch to alternative resolvers, which undermines both compliance and business goals.
For all these reasons, mandated DNS blocking is the wrong tool for public policy enforcement. If online harms need to be addressed, interventions should focus on the content itself, the actors responsible, and measures grounded in due process and international cooperation. The DNS exists to make the Internet usable, not to serve as a mechanism of control. Preserving its universality, reliability, and security is essential to maintaining an open, resilient, and global Internet.
