The Hidden Costs of Widespread DNS Blocking

The Domain Name System, or DNS, is often called the phonebook of the internet. When you type a website name like example.com into your browser, your device asks a DNS resolver to translate that name into the numerical IP address computers use to find each other. Because almost every online activity starts with a DNS query, whoever controls or influences this step can decide whether a site is reachable.

According to the Internet Society, a global nonprofit that works for an open and secure internet, DNS blocking mandates are multiplying. These are legal or regulatory orders that require internet service providers and other network operators to prevent certain domain names from resolving to their IP addresses. Governments and courts around the world use such mandates to block websites for reasons ranging from copyright enforcement to fighting malware, but the Internet Society warns that the growing use of this tool brings serious concerns about security, the openness of the internet, and fragmentation.

The first major concern is security. When a DNS resolver is forced to block a domain, it typically returns a false answer or no answer at all. This can conflict with DNSSEC, the Domain Name System Security Extensions, which digitally signs DNS responses so that users can be sure they are reaching the real site and not a fake one. A blocked domain that would normally have a valid DNSSEC signature suddenly fails validation. Many users, seeing an error, may simply disable DNSSEC checking or switch to a resolver that does not validate signatures. Both actions make them far more vulnerable to DNS spoofing and phishing attacks, where criminals redirect users to fraudulent websites to steal passwords or install malware.

Another worry is the openness of the internet and the risk of fragmentation. Different countries impose different DNS block lists, so the same website may be reachable in one country but not in another. This creates a splintered or fragmented internet, sometimes called the splinternet, where users in different regions see different versions of the web. Blocking at the DNS level can also have collateral damage. If a blocked domain shares an IP address with many other legitimate websites, blocking the name can make all of them unreachable, even though only one was targeted. This can hurt small businesses and ordinary users who rely on those services.

Then there is the issue of privacy and surveillance. Traditional DNS queries are sent in plain text, meaning anyone on the network path, including internet providers, governments, or malicious actors, can see which sites you are trying to visit. DNS blocking often works by inspecting these plain text queries, which reinforces the idea that your browsing is being monitored. To counter this, privacy advocates recommend encrypted DNS protocols. DNS over HTTPS, or DoH, wraps DNS queries in the same encryption used for secure websites, while DNS over TLS, or DoT, uses a dedicated encrypted connection. These protocols prevent third parties from seeing or tampering with your name lookups, but some blocking mandates now also target encrypted DNS providers.

For users and website owners who want to stay secure and keep the internet open, there are practical steps to take. You can configure your device or router to use a trusted, privacy-respecting encrypted DNS resolver. You can turn on DNSSEC validation in your operating system or browser where it is available. If you encounter a blocked site, double-check that you are not being tricked into visiting a fake alternative. And always keep your software updated to protect against DNS-related vulnerabilities. For those who want to combine reachability with privacy, a service like AEU DNS (https://aeu-dns.com) provides encrypted DNS queries and a no-logs policy, which can help you avoid surveillance and tampering while you browse.