9.9.9.9 is the primary DNS resolver address of Quad9, a non-profit public DNS service. Quad9 blocks domains known to be used for malware, phishing, and other threats using threat intelligence from IBM X-Force and other partners. It does not log personally identifiable information and is headquartered in Zurich, Switzerland.
Privacy note
If 9.9.9.9 appears in a DNS leak test, your system or network is configured to use Quad9. This is generally considered a privacy-respecting choice, but if you're on a VPN and see this address, check whether your VPN is enforcing its own DNS resolver.
Based on geolocation data, 9.9.9.9 is associated with Berkeley, California, United States. IP geolocation is approximate and may differ from the physical server location.