Quad9
DNS service
Quad9 is a global public recursive DNS resolver that aims to protect users from malware and phishing. Quad9 is operated by the Quad9 Foundation, a Swiss public-benefit, not-for-profit foundation with the purpose of improving the privacy and cybersecurity of Internet users, headquartered in Zürich. Quad9 is entirely subject to Swiss privacy law, and the Swiss government extends that protection of the law to Quad9's users throughout the world, regardless of citizenship or country of residence.
Security and privacy
Several independent evaluations have found Quad9 to be the most effective (97%) at blocking malware and phishing domains.
As of June, 2021, Quad9 was blocking more than 100 million malware infections and phishing attacks per day. Quad9's malware filtering is a user-selectable option. The domains which are filtered are not determined by Quad9, but instead supplied to Quad9 by a variety of independent threat-intelligence analysts, using different methodologies. Quad9 uses a reputation-scoring system to aggregate these sources, and removes "false positive" domains from the filter list, but does not itself add domains to the filter list.
Quad9 was the first to use standards-based strong cryptography to protect the privacy of its users' DNS queries, and the first to use DNSSEC cryptographic validation to protect users from domain name hijacking. Quad9 protects users' privacy by not retaining or processing the IP address of its users, and is consequently GDPR-compliant.
The public source identifies “Quad9” as dNS service. This brief keeps that definition visible, then builds a research path around Quad9 and service.
Why this record matters
A short description can identify a subject without explaining its stakes. For “Quad9”, the useful work is to connect “dNS service” to the records capable of establishing context and consequence.
Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated Sep 21, 2026. The linked authority identifier is Q52063654. 1 of 3 selected statements include explicit references; 2 carry qualifiers and 0 use preferred rank. The first chronological checks are 2021.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The lead is largely declarative, so disagreement and counter-evidence require a deliberate search beyond the opening account. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
How to read it
Use the entry as an orientation point, then follow its citations and revision history. Names, dates and institutional relationships should be checked against the original record.
- Subject orientation
- Search vocabulary
- Locating named sources
The closest primary source, responsible institution and strongest cited specialist reference.
Three-step research path
- Establish the record: confirm the title “Quad9”, its source revision and the description used here.
- Expand the search: follow Quad9 primary sources, Quad9 archive and Quad9 research across catalogues and specialist indexes.
- Test the account: compare the strongest cited source with the responsible institution’s current record and note any disagreement.
Questions for further research
- Which source most directly establishes the central claim about “Quad9”?
- What terminology or title could unlock a more precise catalogue search?
- Which institution is responsible for the underlying evidence?
Search terms from this dossier
This entry incorporates text from “Quad9” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.