Why Pi-Hole Fails Most Ad Blocker Tests

You run Pi-Hole. You know it's working because you've seen the query log. You've watched it sinkhole doubleclick.net, caught your smart TV pinging home to Samsung fourteen times an hour, and you feel smug about it. Your setup is tight.

Then you run one of the popular ad blocker tests and score 14 out of 18. Or 7 out of 15. The test tells you your blocker is "weak." It suggests you "upgrade to a real ad blocker" while linking you to whatever browser extension their affiliate deal is with this week.

The test is wrong.

Not "maybe wrong" or "misconfigured." Structurally, architecturally, fundamentally wrong. Most ad blocker tests were designed around browser extensions like uBlock Origin, which work completely differently from DNS-level blockers like Pi-Hole. Running one of those tests with Pi-Hole in the middle gives you a false negative that makes your setup look broken when it's doing exactly what it's supposed to.

This piece breaks down why. If you're frustrated that your Pi-Hole "scores low" on popular tests, or you're a homelab person who wants to verify their setup actually works, stick around. We built a test that handles Pi-Hole correctly, and we're going to walk you through how real protection actually gets measured.

the two layers most tests ignore

Imagine your network as a pipe. Traffic goes out, traffic comes back in. Along the way, several different things can stop bad traffic from reaching you.

The DNS layer is where Pi-Hole lives. Before any connection is made, your device asks "what's the IP for ads.doubleclick.net?" If something is blocking DNS (Pi-Hole, AdGuard Home, NextDNS), that question gets answered with 0.0.0.0 or an NXDOMAIN response. The connection never happens. You never loaded the ad because you never learned where it was.

The browser layer is where uBlock Origin lives. If the DNS lookup succeeds, the browser starts constructing the page. Extensions inspect the HTML and hide specific elements from rendering. If <iframe src="doubleclick.net/ads/..."> shows up, uBlock hides it after the page loads. The request may have already gone out, but you don't see the ad.

These are two completely different blocking strategies, and they catch different things:

Pi-Hole's strength is that it catches things at the network layer, before your browser even considers the request. Every device on your network is protected. Your smart TV, your roommate's iPad, your kid's PlayStation. Pi-Hole doesn't care what runs on them.

But that strength is also the reason ad blocker tests give it a bad score. Let me explain.

how a typical ad blocker test works

Go to one of the popular ones. They work roughly like this.

1. Load a bunch of HTML elements that look like ads. A <div> with id="banner_ad", an <iframe> with a source pointing at a known ad network, a <script src="google-analytics.com/...">.
2. Use JavaScript to check whether those elements rendered on the page, whether the iframes have content, whether the scripts executed.
3. Count how many are blocked. Show a score.

Here's the problem. When uBlock Origin sees a <div id="banner_ad">, its cosmetic filters hide it regardless of whether the network request was blocked. So you pass the test even if the ad domain did resolve and did send content back.

When Pi-Hole sees the same test page, it does its job at DNS time. The browser asks for doubleclick.net, Pi-Hole returns 0.0.0.0, the browser tries to connect and fails. The <iframe> still exists in the DOM but has nothing loaded inside it.

The test script then checks: "is the iframe in the DOM?" YES. It concludes your blocker failed, even though the ad never actually loaded. This is the false positive problem. Pi-Hole is blocking the actual network request. The test is just measuring the wrong thing.

The test sees an iframe with no content and calls your blocker broken. Meanwhile the ad never loaded because your blocker worked perfectly. It's like failing a burglar-alarm test because the burglar never tripped the sensor.

what pi-hole actually catches

Let's be honest about what a well-configured Pi-Hole is very good at:

• Third-party ad domains. DoubleClick, AdSense, Taboola, Outbrain, Criteo, forty-seven others. All sinkholed at DNS.
• Analytics trackers. Google Analytics, Facebook Pixel, Mixpanel, Hotjar, most tracking infrastructure.
• Known malware domains. PhishTank feed, URLhaus, standard DNS threat lists.
• Device telemetry. Your smart TV phoning home. Your Samsung fridge. Your Sonos. Your Ring doorbell. Your kid's Oculus.
• Sneaky CDN-hosted trackers. Plenty of them. Pi-Hole's blocklists catch most of the obvious ones.

That's a lot. For most homes, Pi-Hole alone reduces unwanted network traffic by 30 to 50 percent. It's not nothing. It's the single highest-leverage privacy upgrade you can make for $40 in hardware.

But here's what Pi-Hole can't catch.

what pi-hole probably IS missing

1. DoH and DoT browsers go around you

Modern Chrome, Firefox, and Edge can all be configured to use DNS over HTTPS (DoH). If enabled, the browser doesn't ask your router for DNS resolution. It asks Cloudflare, Google, or Mozilla directly over port 443, the HTTPS port. Your Pi-Hole never sees the query.

This is a huge blind spot. A kid opening Chrome with DoH enabled gets full, unfiltered ad-network access right through your network. Your Pi-Hole log shows nothing because the query never went through your DNS server.

On the piholekiller.com gauntlet, check whether DoH endpoints resolve. Level 2 fires requests at cloudflare-dns.com, dns.google, and ten other public DoH servers. If they succeed, your network isn't blocking DoH.

The fix: block DoH endpoints at your firewall, or use a firewall that intercepts port 443 to those specific hostnames. Pi-Hole alone can't do this without additional network rules. Alternatively, use a DNS filter that's DoH-native from the start, like NextDNS or Control D.

2. Fingerprinters don't need DNS tricks

Fingerprinting is a separate category of tracking that doesn't depend on external requests at all. A fingerprinting script can identify you uniquely using:

• Canvas rendering (every device has subtle pixel differences)
• WebGL renderer info
• AudioContext measurements
• Installed fonts
• Screen resolution + color depth
• Hardware concurrency (CPU cores)
• Battery status (on some browsers)
• Timezone + language settings

All of this happens inside your browser, using JavaScript that's already running. No external domain is queried. Pi-Hole cannot see it and cannot block it. The only defense is browser-level: extensions like uBlock Origin's medium mode, Brave's built-in fingerprint protection, or Tor Browser.

3. Same-domain ad tags

Increasingly, sites serve ads from the same domain as the content. The New York Times serves ads from nyt.com subdomains. YouTube serves pre-roll video ads from youtube.com itself. Pi-Hole can't block nyt.com because that's the legitimate site you want to load.

This is a cat-and-mouse game that Pi-Hole is losing by architecture. DNS filtering is domain-level, and many advertisers have moved to first-party subdomains specifically to defeat it.

4. Pop-under networks rotate domains daily

PropellerAds, Adsterra, PopCash, and the rest of the pop-under advertising industry use domain rotation as a core strategy. Today's tag loads from 12ezo5v60.com. Tomorrow's from ybs2ffs7v.com. Your Pi-Hole blocklist is always chasing yesterday's domains.

Premium blocklists (OISD, Hagezi Pro, OSIRIS) catch some of these, but there's inherent lag. If your blocklist updates weekly and the network rotates daily, six out of seven days your Pi-Hole misses new pop-under domains.

5. Anti-adblock scripts

Some sites detect blockers and either beg you to disable them or refuse to load content. These scripts aren't ads themselves, so blocking them is tricky. Pi-Hole's lists catch some well-known anti-adblock services (BlockAdBlock, FuckAdBlock) but new ones pop up constantly. WASM-based anti-adblock code is particularly slippery because it's harder to filter by URL pattern.

how piholekiller.com tests differently

We built the test specifically to handle the Pi-Hole case correctly. Instead of checking whether HTML elements render, we check whether the actual network requests complete.

The test is a series of HTTP requests to known ad, tracker, fingerprinter, DoH, and malware domains. Each one has a cache-busted URL, so the browser can't serve a stale answer. We wait up to 4 seconds for a response. If the request completes, that's a leak. If it fails (timeout, DNS error, connection refused), that's a block.

Pi-Hole on a DNS request to doubleclick.net:

• Pi-Hole returns 0.0.0.0.
• Browser tries to connect to 0.0.0.0:443.
• Connection fails immediately.
• We mark it as blocked.

This is what you actually want Pi-Hole doing. Our test measures exactly that.

benchmark results from real setups

We ran the full 103-test battery against several common configurations. Here's how they scored.

The takeaway is that Pi-Hole alone is excellent but not complete. To get into the nineties, you need to layer something on top. The cheapest upgrade is a browser extension. The most thorough is a DNS setup that handles DoH bypass natively.

how to score higher

If you tested your setup and landed somewhere in the 60s to 80s, here's how to improve without replacing your whole stack.

1. Layer a browser blocker on top of Pi-Hole

uBlock Origin is free, open source, and catches everything Pi-Hole structurally can't. Fingerprinters, cosmetic ads, same-domain tags, anti-adblock scripts. Adding it to your primary browser is the single biggest score improvement you can make for zero cost.

If you're using Chrome, note that Google is deprecating Manifest V2 (which uBlock uses for its full feature set). The migration to Manifest V3 weakens blockers. Consider switching to Brave or Firefox for your daily browsing. Both maintain uBlock V2 parity.

2. Block DoH at the firewall

If your router supports it, block outbound traffic to known DoH endpoints: cloudflare-dns.com, dns.google, mozilla.cloudflare-dns.com, dns.quad9.net. Most consumer routers don't offer this, which is part of why we're building better hardware.

Alternatively, use a DNS service that's DoH-native, like NextDNS or Control D. These operate at the DoH layer from the start.

3. Use a VPN to block ISP tracking

Your ISP sees every domain you look up, even if Pi-Hole blocks 80 percent of those domains' ads. They know you looked them up. Adding a VPN moves that visibility from your ISP to the VPN operator, so picking the right operator matters more than the marketing suggests.

Mullvad VPN accepts cash, doesn't require an email, and costs about €5 per month. Their no-account model is the gold standard for people who take privacy seriously. They were audited by Cure53 and passed without remediation.

Proton VPN is a solid alternative if you want a free tier to test, or want their VPN + Mail + Pass suite bundled in one subscription. Swiss jurisdiction, no logs, supports Tor over VPN.

4. Run a password manager with unique passwords

Ad networks and fingerprinting are one class of attack. Credential stuffing is another. If you reuse passwords across sites and one of those sites gets breached (LastPass 2022, Twitter, LinkedIn, nine others we could list), attackers can take over your email and cloud storage before you notice.

Bitwarden is open source, free for individuals, and the only password manager we actually recommend without caveats. Avoid LastPass. Avoid anything closed-source that you can't audit.

5. Get your data off the broker sites

Even with perfect blocking and a VPN, your historical data is already on hundreds of broker sites: Spokeo, BeenVerified, Whitepages, Intelius, three hundred others. Someone searches your name, they find your address, phone number, relatives. The damage is already done.

Optery automates the removal process. Files opt-out requests at every broker, tracks compliance, re-checks monthly because brokers re-scrape you. Think of it as Pi-Hole for historical public-records leaks. Set it up once, forget about it, stop seeing your own address in Google searches.

the limitations of any DNS-only blocker (be honest)

Pi-Hole is not a replacement for defense in depth. If you're relying only on Pi-Hole, you are:

• Fine against most mainstream advertising.
• Exposed to fingerprinting, DoH-bypass browsers, same-domain ads, and rotating pop-under networks.
• Fully exposed on devices that use DNS servers you don't control. Anything that hardcodes 8.8.8.8 in its firmware ignores your Pi-Hole.
• Exposed to same-domain telemetry from apps that phone home via HTTPS to their own CDN.

Good security is always layered. Pi-Hole is a crucial layer but not the only one. If an ad blocker test tells you your setup is "perfect" with Pi-Hole alone, it's giving you false confidence.

test your own setup

We built piholekiller.com specifically to give you an honest assessment. It takes about 90 seconds. Runs 103 tests across 6 categories. No login, no data storage, no BS. You can stop at any of the 3 levels if you'd rather not see what leaks on the hardest tier.

If you score under 70, you've got real gaps. If you're in the 70s to 80s, you're doing better than most but you can tighten things further. If you score 90+, you're in the elite 1 percent and we'd like to see your setup (submit to the leaderboard).

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