DNS leak
When name lookups travel to your ISP’s resolver instead of through the tunnel, exposing every domain you visit.
Glossary
Ad-blocking DNS
A resolver run by the VPN provider that refuses to answer lookups for known advertising and tracking domains.
Why it matters
It works on every device on the tunnel, including ones where you cannot install a browser extension.
What most explanations leave out
DNS-level blocking cannot remove ads served from the same domain as the content, so it is weaker than a content blocker in the browser. It also gives the provider a categorised view of your lookups, which is a reason to care about the same provider’s logging policy.
Related terms
No-logs policy
A provider’s commitment not to record which sites you visit, when you connected, or what address you connected from.
Terms are defined here because they appear in our scoring rubric or in provider reviews, not to fill a glossary.