Guides / DNS leak basics — what it is and why VPN users care
DNS leak basics for VPN users
DNS is the phone book of the internet: your device asks which IP matches a website name. A “DNS leak” usually means those lookups still go to your ISP or local resolver instead of through the VPN path you expected.
Why DNS matters for privacy
Even when page content is encrypted with HTTPS, DNS questions can reveal which domains you resolve. If those queries leave via your normal ISP while you believe everything is in the VPN tunnel, you get a partial privacy gap.
Common causes
- VPN not fully connected yet when apps already resolve names
- Split tunneling or OS exceptions sending some traffic outside the tunnel
- Misconfigured custom DNS on the device or router
- IPv6 paths that are not covered the same way as IPv4 (varies by network and OS)
Practical habits with 4U
Wait until 4U shows connected before opening sensitive apps. Avoid mixing random third-party “DNS changer” apps unless you understand them. After major OS updates, reconnect and confirm the VPN status indicator.
Online “leak test” sites can be educational, but results depend on the test method and are not a legal audit of 4U.
This page is educational. It is not a guarantee that every network path on every device is leak-free under all conditions.
Ready to try 4U VPN? Install from the App Store or Google Play — no account required for the free session.
