DNS over TLS (DoT): Enhancing Privacy and Security in DNS Communication

 DoT (DNS over TLS)

What Is DoT (DNS over TLS)?

DNS over TLS (DoT) is a security protocol that encrypts DNS queries using the Transport Layer Security (TLS) protocol. It aims to protect user privacy and prevent tampering by ensuring that DNS traffic between a client and a DNS resolver is encrypted and authenticated.

Why DNS Needs Protection

Traditional DNS queries are sent in plain text over UDP or TCP, which means:

• Anyone on the network (e.g., ISPs, attackers) can see what websites you're visiting.
• DNS responses can be spoofed or altered, leading to phishing or malware attacks.

How DoT Works

1. A client (like your device or router) initiates a DNS query.

2. Instead of sending it over plain UDP, it uses TCP with TLS encryption.

3. The query is sent to a DoT-compatible DNS resolver (e.g., Cloudflare, Google, Quad9).

4. The resolver decrypts the query, processes it, and sends back an encrypted response.

This ensures:

• Confidentiality: No one can read the DNS query in transit.
• Integrity: The response hasn’t been tampered with.
• Authentication: The resolver is verified via TLS certificates.

Key Features of DoT

• Encryption via TLS (port 853).
• System-wide protection (unlike DoH, which is often app-specific).
• Less obfuscation than DoH, making it easier for network admins to manage.

DoT vs. DoH

Benefits

• Improved privacy: Prevents DNS snooping.
• Better security: Protects against DNS spoofing and MITM attacks.
• Compliance-friendly: Easier for organizations to monitor and control.

Limitations

• Not all networks support DoT.
• Requires compatible DNS resolvers.
• Can be blocked or throttled by firewalls.

Adoption

DoT is supported by:

• Android (from version 9) with system-wide DNS settings.
• Linux distributions via systemd-resolved or Unbound.
• DNS providers like Cloudflare (1.1.1.1), Google (8.8.8.8), and Quad9 (9.9.9.9).