What is a DNS adblock test?
A DNS adblock test sends requests toward domains commonly associated with advertising, analytics, or tracking. If your DNS resolver refuses, redirects, or prevents those hostnames from resolving, the browser cannot contact them normally. Running the test from the device and network you use helps confirm whether those rules are active.
This result covers the complete network path. It may reflect Pi-hole, NextDNS, an encrypted private DNS profile, a VPN ad blocker, router firmware, or several layers together. Start by testing your ad blocker, then compare the category breakdown with the rules you expect to be enabled.
How DNS-level blocking works
Before a browser contacts a host, it usually asks a DNS resolver for an address. A filtering resolver checks the requested hostname against its blocklists. Known advertising or tracking domains can be denied before the browser downloads their scripts, pixels, or media.
That approach protects more than one browser and can cover apps, smart devices, and systems where extensions are unavailable. It also has an important limit: DNS sees a hostname, not the individual page element or complete URL path.
Network blocking is not cosmetic filtering
A DNS filter can stop a third-party ad domain but usually cannot remove the empty space left in a webpage. Browser extensions can apply cosmetic rules that hide those placeholders.
What this test can detect
The test can show that representative ad, analytics, social, vendor, and tracker hosts were blocked or reachable. Consistently blocked hosts are evidence that some protection layer intercepted those requests. Reachable hosts indicate gaps in the combined setup during that run.
It cannot prove which resolver answered the DNS query, attribute a block to one product, or guarantee every app uses the same DNS path. Browsers and VPNs can use their own encrypted DNS settings, bypassing a router or local resolver.
Pi-hole and NextDNS testing
For a Pi-hole adblock test, confirm that the device is actually using Pi-hole as its resolver. Check its query log while running the test: requested domains should appear, and blocked entries should match the relevant lists. If nothing appears, DHCP settings, hard-coded DNS, a VPN, or browser secure DNS may be routing around Pi-hole.
For a NextDNS adblock test, verify that the active device or browser uses the intended configuration ID. Review the NextDNS logs and enabled privacy lists. Profiles can differ by device, network, or browser, so test each environment you depend on.
VPN and router-level ad blocking
A VPN may send DNS traffic through its own resolver and add ad or threat filtering. Make sure the feature is enabled, connect the VPN, and rerun the test. Disconnecting for a comparison can show whether the VPN changes the result, but change one layer at a time.
Router filtering can protect a household without device-by-device setup, but only when clients use the router’s chosen resolver. Encrypted DNS in a browser or operating system may bypass it. Review the router’s client and DNS settings rather than assuming every connected device follows the same path.
Why extensions and DNS blockers get different results
Extensions can evaluate full request URLs, resource types, and page context. They may hide cosmetic elements and apply site-specific rules. DNS blockers decide at hostname level and work beyond the browser, but they cannot safely block a shared first-party domain just because one path serves an ad.
Different results are therefore expected. A browser extension such as the one covered in the uBlock Origin test can complement DNS protection rather than duplicate it.
How to improve DNS blocking
- Confirm which resolver the device and browser are actually using.
- Enable a maintained advertising and privacy list appropriate for your environment.
- Check logs for test domains and rule conflicts.
- Review allowlists, bypass lists, and VPN split-tunneling settings.
- Flush the device DNS cache or reconnect after configuration changes.
- Run the test again and use the score guide to compare categories.
Aggressive lists can break sign-in, payments, media, or app telemetry required for normal operation. Prefer maintained defaults, add focused rules, and keep a record of custom exceptions. Retest from both Wi-Fi and mobile data when the device switches between different resolvers.