Your home network’s DNS requests are probably bouncing around the internet like a lost ping pong ball, hitting up Google, Cloudflare, or your ISP’s servers. Pi-hole, however, can catch all those requests and keep them local, giving you a ton of control and visibility.
Let’s see Pi-hole in action. Imagine you’ve just installed Pi-hole, and your router is still pointing clients to your ISP’s DNS.
# On a client machine (e.g., your laptop)
dig @192.168.1.1 google.com
This dig command queries your router at 192.168.1.1 for google.com. The router, in turn, forwards this request to its configured upstream DNS server (likely your ISP’s). You’ll see a typical DNS response, but the query didn’t go through Pi-hole.
Now, let’s point your router’s DHCP settings to your Pi-hole server (let’s say its IP is 192.168.1.2). After clients renew their DHCP lease (or you manually set their DNS to 192.168.1.2), you’d run the same command again:
# On a client machine, *after* DHCP renewal or manual DNS change
dig @192.168.1.2 google.com
This time, the dig command directly queries your Pi-hole. If Pi-hole is configured with an upstream DNS server (like 1.1.1.1), it will then query that server. The crucial difference is that Pi-hole now sees this request. You’ll immediately notice new entries in your Pi-hole dashboard’s "Query Log," showing google.com being resolved via 192.168.1.2.
The problem Pi-hole solves is the opacity and lack of control over your network’s internet traffic. Every device on your network, from your smart TV to your phone, makes DNS requests. Without Pi-hole, these requests are opaque, contributing to trackers and potentially less private browsing. By acting as your network’s sole DNS resolver, Pi-hole intercepts every single one of these requests.
Here’s how it works internally. When a device on your network asks for example.com, the request first hits your router. If your router is configured to hand out your Pi-hole’s IP address (192.168.1.2) via DHCP, the device sends the DNS query to 192.168.1.2. Pi-hole’s DNS resolver then checks its local cache. If the answer is there, it responds immediately. If not, it forwards the query to one of its configured "upstream DNS servers" (e.g., Cloudflare’s 1.1.1.1 or Google’s 8.8.8.8). Once Pi-hole receives the answer from the upstream server, it caches it for future requests and forwards it back to the original client device. The "magic" is that Pi-hole logs all these queries before they even reach the upstream servers. This log is what powers its blocking capabilities and provides detailed network insights.
The exact levers you control are primarily within the Pi-hole web interface. Under "Settings" -> "DNS," you choose your upstream DNS providers. These are typically public DNS servers like Cloudflare, Google, OpenDNS, or Quad9. You can select multiple, and Pi-hole will use them in a round-robin fashion or based on their latency. Crucially, under "Settings" -> "Blocklists," you add URLs of DNS blocklists (lists of known ad-serving or tracking domains). Pi-hole downloads these lists periodically and adds all the domains within them to its internal blocklist. When a client requests a domain that’s on this blocklist, Pi-hole doesn’t even bother asking an upstream server; it just returns an "unreachable" IP address (usually 0.0.0.0).
The network configuration is the key. You’re not just installing Pi-hole; you’re re-architecting your network’s DNS. The most common way to route all traffic through Pi-hole is to configure your router’s DHCP server. Within your router’s admin interface, find the DHCP settings. You’ll typically see fields for "Primary DNS Server" and "Secondary DNS Server." You should set your Pi-hole’s IP address (e.g., 192.168.1.2) as the only DNS server provided by DHCP. This forces every device that gets an IP address from your router to use Pi-hole for DNS. If you have devices with static IPs or devices that don’t use DHCP, you’ll need to manually configure their DNS settings to point to your Pi-hole.
The most surprising thing about routing all traffic through Pi-hole is how much less traffic actually leaves your local network for DNS resolution. When you query a domain that Pi-hole has recently resolved, the response comes instantly from Pi-hole’s cache, bypassing the upstream DNS entirely. This can lead to a noticeable speed improvement for repeated lookups and significantly reduces the load on your internet connection for DNS traffic. It’s like having a local library for internet addresses instead of always calling the central registry.
Once you have all devices routing through Pi-hole and blocking is working, the next thing you’ll likely encounter is that some sites or services stop working correctly because Pi-hole is blocking a domain they depend on.