How DNS ad blocking works
A typical web page or app does not just load its own content. It also contacts advertising networks, analytics services and tracking pixels, each served from its own domain. A DNS ad blocker keeps a list of those domains and answers lookups for them with 0.0.0.0 or NXDOMAIN. The advert or tracker simply fails to load, while the rest of the page continues normally.
This approach differs from a browser extension. An extension can see and hide individual elements on a page, but it only works inside that browser. DNS blocking works for every app and every device that uses the resolver, from a phone game to a streaming box, without installing anything.
What you can expect
With ad and tracker blocking enabled, many banner adverts, pop-up networks and analytics beacons stop loading. Smart TVs and streaming devices, which often contact telemetry domains constantly, become noticeably quieter in the query log. Pages may load faster because fewer third-party requests are made, and less data about your browsing is sent to advertising companies.
- Fewer display adverts in browsers and apps
- Less telemetry from smart TVs, consoles and IoT devices
- Fewer third-party analytics and tracking requests
- Malicious advertising (malvertising) blocked when it uses listed ad domains
What DNS blocking cannot remove
Some adverts are served from the same domain as the content itself. Large video platforms and social networks commonly do this, and blocking the domain would block the service. DNS filtering cannot remove those ads without breaking the site, so you will still see some advertising there. It also cannot hide empty boxes left on a page where an advert would have been; that cosmetic clean-up needs a browser extension.
If you need complete ad removal inside a browser, combine DNS blocking with a reputable browser extension. DNS covers the rest of the network.
Avoiding broken sites and apps
Aggressive ad lists occasionally block a domain that a site needs to work, for example a login or payment step that passes through a tracking domain, or a shopping link that redirects through an affiliate network. If something breaks, check the query log for blocked lookups at the time of the problem and add the domain to your allowlist. [VERIFY: which ad and tracker list(s) are used and whether ad blocking is a separate switch in the dashboard]
Privacy benefits
Trackers build profiles by recognising the same device across many sites and apps. Each blocked tracking request is one less data point in that profile. DNS blocking does not make you anonymous, because websites you visit still see your IP address and can track you with their own first-party tools, but it reduces the amount of cross-site tracking considerably.
For full privacy on the way to the resolver, combine ad and tracker blocking with encrypted DNS, so that the list of domains you look up cannot be read by others on the network path.
Testing before enabling it everywhere
If you manage a business network, enable ad and tracker blocking on a test network or for a small group first. Use the most important business tools for a few days, check the query log for blocked domains during normal work, and allowlist anything required. Once the list of exceptions is stable, roll the setting out to everyone. At home, simply switch it on and allowlist anything that breaks.
Ads, consent and legitimate publishers
Many websites fund their content through advertising. Blocking ads at the network level is your choice, and some readers choose to allowlist sites they want to support. Your allowlist makes that simple.
Fewer requests, less bandwidth
Every blocked advert or tracker is a request that never leaves your network. On busy networks with many devices, or on metered connections such as 4G backup links and satellite internet, that reduction can be noticeable. On mobile networks it can also save data.
Good for home and office
At home, ad and tracker blocking makes smart TVs and children's tablets less noisy and reduces exposure to inappropriate advertising. In an office it reduces bandwidth, removes a vector for malvertising and keeps staff devices from leaking browsing data to advertising networks. In both cases the configuration is the same: one switch for the whole network.