DNS over HTTPS (DoH) and DNS over TLS (DoT): Privacy, Security, and Performance Deep Dive

The Domain Name System (DNS) is the fundamental directory service of the internet. It translates human-readable domain names (like google.com) into the numerical IP addresses that computers use to communicate. Traditionally, DNS queries are sent in plain text, making them vulnerable to eavesdropping and manipulation. DNS over HTTPS (DoH) and DNS over TLS (DoT) are emerging protocols designed to address these vulnerabilities by encrypting DNS queries and responses.

What is DNS over HTTPS (DoH)?

DoH encrypts DNS queries using the HTTPS protocol, the same protocol used for secure web browsing. This means that your DNS queries are protected from interception by your internet service provider (ISP), your employer, or anyone else who might be monitoring your network traffic. DoH typically uses port 443, the standard port for HTTPS, making it easy to deploy and integrate with existing infrastructure.

What is DNS over TLS (DoT)?

DoT is similar to DoH, but it uses the TLS protocol instead of HTTPS. While both achieve encryption, DoT is often considered a simpler implementation, particularly for devices with limited resources. However, DoH generally offers greater flexibility and potential for integration with other services.

Key Differences between DoH and DoT

Feature	DoH	DoT
Protocol	HTTPS	TLS
Port	443	853 (typically)
Flexibility	Higher; allows for additional features like caching and extensions	Lower; more straightforward implementation
Deployment	Easier due to widespread use of port 443	Requires configuring port 853

Benefits of Using DoH and DoT

Enhanced Privacy: Your DNS queries are encrypted, preventing your ISP and other entities from seeing what websites you're accessing.
Improved Security: Encryption protects against DNS spoofing and cache poisoning attacks, reducing the risk of being redirected to malicious websites.
Increased Reliability: In some cases, DoH and DoT can improve DNS query reliability by using multiple resolvers.

Potential Drawbacks

Performance: While typically negligible, encrypted queries may occasionally introduce a slight performance overhead.
Censorship Circumvention: The use of DoH and DoT can make it harder for governments and organizations to censor internet access.
Dependence on a Third-Party Resolver: You rely on the security and privacy practices of your chosen DNS resolver.
Firewall Compatibility: Some firewalls might block DoH/DoT traffic unless properly configured.

Choosing a DoH/DoT Provider

Selecting a reputable DoH/DoT provider is crucial. Consider factors like their privacy policy, security practices, location, and performance. Popular options include Cloudflare DNS, Google Public DNS, and Quad9. It's important to research and select a provider that aligns with your privacy and security needs.

Configuring DoH/DoT on Your Devices

The process for configuring DoH or DoT varies depending on your operating system and device. Most modern operating systems offer built-in settings to change your DNS server. You can also configure DoH/DoT at the router level for device-wide protection. Consult your device's documentation for specific instructions.

Conclusion

DoH and DoT are important advancements in internet privacy and security. By encrypting DNS traffic, they help protect users from eavesdropping and various attacks. While some minor drawbacks exist, the benefits often outweigh the risks for many users. Carefully consider your needs and choose a reputable provider to maximize the benefits of these powerful protocols.