Pi-hole is a free, open-source DNS sinkhole. The name comes from its original target hardware — a Raspberry Pi — though it runs fine on almost anything: an old laptop, a virtual machine, a container, a home server. You point your router at it, and it becomes the resolver every device on your network uses to turn domain names into IP addresses. That position, sitting astride every lookup, is what makes it powerful.
The premise is simple. Almost everything on the modern web starts with a domain name. Before your browser can load an ad, a tracking pixel, or telemetry, it has to resolve a hostname like ads.example-tracker.com into an IP address. If your DNS server simply refuses to answer for known tracking domains, the connection never gets made. No IP, no request, no tracker.
How DNS Sinkholing Works
Normally, DNS resolution is a faithful translator: you ask for a domain, it returns the real address. A sinkhole breaks that faithfulness on purpose, but only for domains on a blocklist.
When a device asks Pi-hole to resolve a domain, Pi-hole checks it against its blocklists. For an allowed domain, it forwards the query to an upstream resolver and returns the real answer. For a blocked domain, it returns a non-answer — typically 0.0.0.0 or NXDOMAIN ("this domain does not exist"). The requesting device tries to connect to nowhere, the request fails instantly, and the ad or tracker simply never appears.
A browser extension only works inside that browser. DNS sinkholing works one layer down, at the network level — so it filters your smart TV, your phone's apps, background telemetry, and embedded devices that have no concept of "extensions." If it makes a DNS query on your network, it's subject to the blocklist.
The blocklists themselves are community-maintained text files of known advertising, tracking, and malware domains. Pi-hole ships with sensible defaults and lets you add curated lists. The size of your list is a tuning decision, not a "bigger is better" race — overly aggressive lists break legitimate sites and create maintenance headaches.
What Pi-hole Does Well
- Network-wide coverage. One install protects every device, including ones you can't configure individually.
- Kills background telemetry. Many apps and smart devices phone home constantly. If those endpoints are blocked at DNS, the chatter stops.
- Visibility. Its dashboard shows exactly which domains your devices are querying and how often — frequently a genuinely unsettling look at how much your "idle" devices talk to the internet.
- Speed and lightness. Blocked lookups fail instantly, and cached lookups are fast. It runs comfortably on minimal hardware.
- Custom local DNS. You can also use it to name devices on your own network, a nice side benefit.
What Pi-hole Does Not Do
This is where honesty matters, because Pi-hole is often oversold. DNS blocking is coarse. It operates on whole domains, and it has hard limits:
| Limitation | Why it happens |
|---|---|
| Can't block in-page ads from first-party domains | If ads are served from the same domain as the content (as on some large platforms), blocking the domain breaks the site too. DNS can't filter part of a domain. |
| Defeated by hardcoded resolvers | Some devices ignore your network's DNS and use their own (e.g. a hardcoded 8.8.8.8 or DNS-over-HTTPS). They bypass the Pi-hole entirely unless you force-redirect at the router. |
| No payload inspection | It sees domain names, not content. It can't strip a tracking parameter from a URL or sanitize a page. |
| Not a privacy shield for your traffic | It blocks some destinations; it does not hide what you do from your ISP or encrypt your connection. That's a different job. |
The hardcoded-resolver problem is the big one in 2026. As more apps and operating systems adopt DNS-over-HTTPS with their own baked-in providers, a Pi-hole on your LAN can be quietly skipped. The countermeasure is to block outbound DNS at your router and force all queries through the Pi-hole — but that's an extra step many people miss, and it can itself break DoH-dependent apps.
Pi-hole and Encrypted DNS
A common confusion: doesn't Pi-hole conflict with encrypted DNS? Not necessarily — they solve different problems and can be combined. Pi-hole decides what to answer; encrypted DNS decides how the query travels.
A well-configured setup runs Pi-hole as the local resolver for filtering, then forwards its allowed queries upstream over an encrypted transport — DNS-over-HTTPS or DNS-over-TLS — using a tool like cloudflared or a DoH proxy alongside Pi-hole. Your devices get filtering and your upstream queries are encrypted against your ISP. If you're weighing the transport options, our comparison of encrypted DNS protocols covers the trade-offs.
Pi-hole is a filter, not a tunnel. It decides which domains get an honest answer; it doesn't, by itself, hide your queries from anyone watching the wire. Treat those as two separate layers.
Where It Fits in a Privacy Stack
Think of Pi-hole as one layer of defense in depth, not a complete solution. It's excellent at reducing the volume of tracking and telemetry across your whole home, and the visibility it provides is genuinely educational. But it doesn't encrypt your traffic, doesn't protect you away from home, and can be bypassed by determined apps.
A reasonable layered approach looks like this:
- Pi-hole for network-wide domain-level blocking at home.
- Encrypted DNS upstream so your ISP can't read your remaining queries.
- A browser-based content blocker for the fine-grained, in-page filtering Pi-hole can't do.
- End-to-end encrypted communication tools for the content that matters most — because no amount of DNS filtering protects the contents of your messages and email.
That last point is worth dwelling on. DNS-layer defenses shape the metadata environment — which servers your devices contact — but they say nothing about whether your actual conversations are readable. Blocking trackers reduces who can build a profile of your behavior; end-to-end encryption is what keeps the substance of your communication private regardless of which network you're on. Pi-hole is a strong, satisfying first layer. Just don't mistake it for the whole stack.