DNS over HTTPS (DoH): How it Works and Why It Matters

DNS, or the Domain Name System, is the internet's phonebook. It translates human-readable domain names (like google.com) into machine-readable IP addresses (like 172.217.160.142) that computers use to communicate. Traditionally, this lookup happens over UDP (User Datagram Protocol), a relatively simple and fast protocol, but also one that lacks security and privacy features.

DNS over HTTPS (DoH) addresses these shortcomings by encrypting DNS queries and responses using HTTPS, the same protocol that secures your web browsing. This means your DNS requests are hidden from your internet service provider (ISP), potential eavesdroppers on your network, and even your own router (depending on your setup).

How DoH Works: A Step-by-Step Guide

1. Your Device Initiates a Query: When you type a website address into your browser, your device sends a DNS query to a DoH-enabled resolver.
2. HTTPS Encryption: Unlike traditional DNS over UDP, this query is sent over an encrypted HTTPS connection. This means the query, including the domain name you're looking up, is encrypted before it leaves your device.
3. The DoH Resolver Processes the Query: The DoH resolver receives your encrypted query, decrypts it, and then looks up the corresponding IP address using its DNS databases.
4. Encrypted Response: Once the resolver finds the IP address, it sends the response back to your device, also encrypted over HTTPS.
5. Your Device Decrypts the Response: Your device receives the encrypted response, decrypts it using the same encryption key, and then uses the IP address to connect to the website.

The key difference is the use of HTTPS. This ensures confidentiality, integrity, and authenticity of the DNS communication. Let's break down the benefits:

Benefits of Using DoH

• Enhanced Privacy: Your ISP and other network observers cannot see which websites you're visiting through your DNS queries.
• Improved Security: HTTPS encryption protects against DNS spoofing and other attacks that can redirect you to malicious websites.
• Resistance to Censorship: DoH can help bypass certain forms of DNS censorship, allowing you to access websites that might be blocked otherwise.
• Faster Connections (Potentially): Some DoH providers offer optimized server infrastructure leading to faster resolution times.

How to Enable DoH

Enabling DoH depends on your operating system and browser. Most modern browsers (Chrome, Firefox, Edge) offer built-in settings to enable DoH. You can usually find these settings under the privacy or network settings within the browser's preferences. Many routers also support DoH, offering network-wide encryption for all devices connected to the router. Some popular DoH providers include Cloudflare (1.1.1.1), Google Public DNS (8.8.8.8), and Quad9 (9.9.9.9). You should be aware of the privacy policies of each provider before selecting one.

Potential Drawbacks

• Potential for Abuse: Malicious actors could potentially use DoH to evade network security measures.
• Dependence on a Third-Party: You are relying on the DoH provider to maintain the security and privacy of your DNS queries.
• Compatibility Issues: Older devices or systems may not support DoH.
• Performance Issues (in some cases):While often faster, network configurations or server locations can lead to slower resolution in some cases.

Conclusion

DNS over HTTPS is a significant advancement in internet security and privacy. By encrypting DNS traffic, it protects your online activity from unwanted surveillance and malicious attacks. While not without potential drawbacks, the benefits generally outweigh the risks for most users. If you're concerned about your online privacy, enabling DoH is a simple and effective step you can take to enhance your security posture.