What Is DNS-over-HTTPS (DoH) and Why Does It Matter for Privacy?

The Hidden Flaw of Traditional DNS

Every time you type a web address into your browser, your operating system sends a Domain Name System (DNS) query to convert that human-readable domain name (like example.com) into a machine-routable IP address.

By default, traditional DNS queries are transmitted in plaintext over UDP port 53. This means:

• Your Internet Service Provider (ISP) logs every domain you visit, creating an exact browsing history profile.
• Network Administrators on local Wi-Fi networks can see what sites you connect to.
• Malicious Actors can perform DNS spoofing and cache poisoning attacks to redirect you to phishing websites.

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How DNS-over-HTTPS (DoH) Works

DNS-over-HTTPS (DoH) resolves this privacy vulnerability by wrapping standard DNS requests inside an encrypted HTTPS session (standard port 443) using TLS.

Key Benefits of DoH:

1. Confidentiality: Eavesdroppers on your local network or ISP cannot see which domain names you are requesting.
2. Integrity & Authenticity: Digital signatures ensure DNS answers cannot be intercepted or altered in transit.
3. Port Blending: Because DoH uses standard HTTPS port 443, network firewalls cannot easily single out and block DNS traffic without blocking all secure web browsing.

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DoH vs DoT: What Is the Difference?

| Feature | DNS-over-HTTPS (DoH) | DNS-over-TLS (DoT) | | :--- | :--- | :--- | | Standard Port | 443 (Standard HTTPS) | 853 (Dedicated Port) | | Protocol Layer | HTTP/2 or HTTP/3 over TLS | Direct TLS tunnel | | Firewall Resistance | High (blends with web traffic) | Medium (easily blocked on port 853) | | Browser Support | Native in Chrome, Firefox, Safari | Configured at OS/Router level |

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How to Enable Encrypted DNS in Your Browser

Modern browsers make it seamless to activate DoH:

• Google Chrome / Brave / Edge: Go to Settings → Privacy and security → Security → Use secure DNS and choose a trusted provider like Cloudflare (1.1.1.1) or Quad9 (9.9.9.9).
• Mozilla Firefox: Go to Settings → Privacy & Security → DNS over HTTPS and select Max Protection.

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Testing Your DNS & Network Privacy

After activating DoH, verify that your network connections do not leak your identity:

• Perform an IP Check to verify your visible public network address.
• Run a WebRTC Leak Test to ensure browser multimedia protocols are properly shielded.
• Test your connection speed with the WhatsMyDevice Speed Test to verify zero latency overhead.