How to Use the DNS Leak Test

Understand what the DNS leak test shows, how to read the results, and how to share them with CleanBrowsing support for fast troubleshooting.

Step 1: What is a DNS Leak?

Every time you visit a website, your device sends a DNS query to translate the domain name (like google.com) into an IP address. Normally, these queries go to whichever DNS server you've configured — in your case, CleanBrowsing.

A DNS leak happens when some or all of your DNS queries bypass your configured DNS and go to a different server instead, typically your ISP's default DNS. When this happens:

  • CleanBrowsing's content filtering may not be applied to all traffic
  • Your ISP can see every website you visit
  • Some devices or apps may bypass your DNS filtering entirely

The DNS leak test detects exactly which DNS servers are handling your queries, so you can verify that CleanBrowsing is active and no queries are leaking.

Step 2: Run the Test

Open the DNS Leak Test page. You'll see your public IP address detected automatically at the top of the page.

Click "Run Extended Test" to start. The test works by sending 30 DNS probes through your browser. Each probe forces a DNS lookup through a unique subdomain, which allows the test to identify every DNS resolver in the chain — even if multiple resolvers are involved.

The test takes about 15–20 seconds to complete. You'll see a progress bar as probes are sent, followed by the results.

Step 3: Your Public IP Address

At the top of the page, you'll see your public IP address along with your ISP name and approximate location. This is the IP address that websites and DNS servers see when your device connects to the internet.

This information is important for support because:

  • If you have a paid CleanBrowsing plan, your public IP must match the one registered in your dashboard for filtering to work
  • If you're behind a CGNAT, your public IP may change frequently, which can affect filtering
  • The ISP name helps us determine if your provider is intercepting DNS traffic

Step 4: Connection Information

The Connection Information card shows diagnostic details about your DNS configuration:

  • Connected to CleanBrowsing: Whether any of your DNS resolvers belong to CleanBrowsing. Shows Yes or No after the test completes.
  • Using DNS over HTTPS (DoH): Whether your browser can reach CleanBrowsing's encrypted DNS endpoint. This is checked automatically when the page loads.
  • Using DNS over TLS (DoT): DoT operates at the system level and cannot be detected from a browser. If you configured DoT, verify it using command-line tools.
  • Filter Profile: If CleanBrowsing is detected, the test identifies whether you're on the Family/Adult filter or the Security filter.
  • AS Name / AS Number: Your ISP's network identification. Useful for diagnosing ISP-specific routing issues.

Step 5: DNS Resolvers

The DNS Resolvers table is the core of the leak test. It lists every DNS server that handled your queries during the test. For each resolver, you'll see:

  • IP Address: The resolver's IP. CleanBrowsing resolvers are highlighted in green with a CleanBrowsing badge.
  • Hostname: The reverse DNS name of the resolver (e.g., family-filter-dns.cleanbrowsing.org).
  • ISP: The organization operating the resolver.
  • Country: Where the resolver is located geographically.

Ideally, you should see only CleanBrowsing resolvers (IPs in the 185.228.168.x or 185.228.169.x range). If you see other resolvers alongside CleanBrowsing, you have a partial DNS leak.

Step 6: Reading the Results

All CleanBrowsing — You're Protected

If every resolver in the table is CleanBrowsing, you'll see a green success banner: "CleanBrowsing DNS detected." Your DNS filtering is working correctly. No action needed.

Mixed Resolvers — Partial Leak

If you see CleanBrowsing resolvers and your ISP's resolvers, you have a partial DNS leak. Some queries are filtered, but others bypass CleanBrowsing. Common causes:

  • DNS configured on the device but not the router (other devices on the network leak)
  • A browser using its own DNS-over-HTTPS setting that overrides your system DNS
  • IPv6 DNS not configured (many devices prefer IPv6 when available)
  • A VPN or proxy that uses its own DNS
No CleanBrowsing — Not Protected

If no CleanBrowsing resolvers appear, your DNS configuration isn't active. You'll see a warning banner. Check your setup and make sure DNS is configured correctly at the router or device level.

No Resolvers Detected

Occasionally the test detects zero resolvers. This usually means your DNS is routed through an encrypted tunnel or privacy proxy that blocks the test probes. Try running the test from a different browser or device.

Step 7: Share Results with Support

After the test completes, you'll see a "Share Results with Support" button below the resolver table. Here's how to use it:

  1. Click "Share Results with Support"
  2. A shareable link will be generated (e.g., cleanbrowsing.org/dnsleaktest?r=abc12345)
  3. Click "Copy" to copy the link to your clipboard
  4. Paste the link into your email to support@cleanbrowsing.org

When our support team opens your link, they'll see exactly what you saw: your public IP, ISP, DNS resolvers, connection diagnostics, and whether CleanBrowsing was detected. This gives us everything we need to diagnose the issue without asking you to take screenshots.

What's Included in the Shared Results
  • Your public IP address at the time of the test
  • All DNS resolvers detected during the test
  • Whether CleanBrowsing was active
  • Your ISP and approximate location
  • Timestamp of when the test was run

Shared results are stored for 30 days, then automatically deleted.

URL Hash Sharing

The test also encodes your results into the URL hash (the # part of the URL) automatically after completion. You can copy the full URL from your browser's address bar as an alternative way to share. This method doesn't require server storage — the data is embedded directly in the URL.

Step 8: Common Issues & Next Steps

"I set up CleanBrowsing but the test shows my ISP's DNS"

Your DNS configuration isn't being applied. The most common causes:

  • Router DHCP override: Your router's DHCP is pushing ISP DNS to devices. Configure DNS on the router itself, not just individual devices.
  • Browser DoH: Chrome, Edge, and Firefox can override system DNS with their own DoH provider. Check your browser's secure DNS settings.
  • Cached DNS: Old DNS entries may be cached. Clear your DNS cache and re-test.
"The test shows CleanBrowsing but filtering doesn't seem to work"

If CleanBrowsing is detected but sites aren't being blocked:

  • Check which filter profile you're using — the Security filter only blocks malware/phishing, not adult content
  • On paid plans, verify your public IP matches the one in your dashboard
  • The site may be allowlisted in your custom rules
  • The site may not yet be categorizedreport it to support
"I see both CleanBrowsing and other resolvers"

A partial leak. See our guide on preventing filter bypass. The most effective fix is using DNS over HTTPS (DoH) or configuring DNS at the router level with firewall rules to block DNS bypass.

Additional Diagnostic Tools

Need more help?

Contact our support team for assistance.

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