Short answer: To check for DNS leaks on iPhone, connect your VPN, then visit a DNS-leak test site in Safari and look at which servers and which network/ISP show up. If you see your home ISP's name or a server you didn't choose, your DNS queries are leaking outside the tunnel.
How to check for DNS leaks on iPhone
- Connect your VPN and confirm it shows as active in Settings.
- Open a DNS-leak test site in Safari (search “DNS leak test”).
- Run the standard or extended test and read the results.
- Check the server owner/ISP. If your home internet provider's name appears — or a location that isn't your VPN's — DNS is leaking.
- Re-test on cellular and on public Wi-Fi, since leaks can appear on one network and not another.
How do I know if my VPN is leaking DNS?
Your VPN is likely leaking DNS if the test shows DNS servers belonging to your ISP rather than your VPN provider, or if your real location/ISP is revealed while the tunnel is connected. The tunnel may encrypt traffic while DNS lookups quietly take a different path.
What to do about it
- Enable any “use VPN DNS” or DNS-protection setting your app offers.
- Use a tool that handles DNS resolution inside the protected path rather than handing it to the local network.
- Avoid split configurations where some apps bypass the tunnel unintentionally.
Where Casper's Cloak fits
Casper's Cloak combines DNS/network filtering with an encrypted WireGuard tunnel and kill-switch-style tunnel hardening, so DNS resolution and filtering are handled within Casper's protected path rather than left to the local network. It also adds system-wide ad/tracker blocking and AI threat detection on iPhone, Android, and Mac. See how Casper protects DNS and traffic →