DNS over TLS (DoT) is a modern, encrypted DNS protocol that enhances privacy and security by wrapping DNS queries in TLS encryption. At CyberFOX, our DoT implementation goes beyond the standard: it supports UUID-based device tracking and integrates seamlessly with our DNS filtering infrastructure by converting DoT traffic to DoH at the resolver level.

This article explains how DoT works, its benefits and limitations, and when to consider using DNS over HTTPS (DoH) or the CyberFOX Agent instead.

What Is DNS over TLS (DoT)?

DoT encrypts DNS queries using the TLS protocol over port 853, shielding them from interception or tampering. Unlike traditional DNS (which uses plaintext over port 53), DoT ensures that DNS traffic is private and secure from the moment it leaves the device.

Key Benefits of CyberFOX DoT

End-to-End Encryption

DoT protects DNS queries from being read or modified by third parties, including ISPs, attackers, or misconfigured networks.

UUID-Based Device Tracking

CyberFOX’s DoT implementation supports UUID tracking, enabling:

• Per-device DNS policy enforcement
• Consistent visibility across networks
• Granular logging and audit trails

This capability is typically associated with agent-based DoH solutions, but CyberFOX also brings it to DoT, without requiring an endpoint agent.

Improved Stability in Managed Networks

DoT can resolve issues such as:

• DNS resolution failures after agent installation
• Filtering policies not applying correctly
• Conflicts with ISP-level DNS filtering (e.g., eero Secure blocking port 53)

Considerations and Limitations

Port-Based Blocking

DoT uses a dedicated port (853), which makes it easier to detect and block on restrictive networks. This can cause issues on public Wi-Fi, captive portals, or networks with aggressive firewall rules.

Device Compatibility

• Google Pixel and some Android builds default to DoT.
• Samsung and other Android vendors increasingly support DoH.
• macOS and iOS support DoT via configuration profiles, but DoH is more widely integrated into browsers and apps.

When to Use DoH Instead

DNS over HTTPS (DoH) is ideal for:

• Devices that frequently connect to public or restricted networks
• Environments where port 853 is blocked
• Scenarios requiring maximum privacy and firewall evasion

DoH uses port 443 (HTTPS), making it indistinguishable from regular web traffic and far more resistant to blocking or redirection.

When to Use the CyberFOX Agent

The CyberFOX Agent is a lightweight endpoint service that:

• Sets DNS to 127.0.0.1
• Encrypts queries using DoH
• Assigns a UUID to each device
• Manages fallback behavior and policy enforcement

The agent is ideal for:

• Roaming users
• Devices requiring persistent policy enforcement
• Environments where DNS must remain encrypted regardless of network conditions

Summary: DoT vs. DoH vs. Agent

Final Thoughts

CyberFOX’s implementation of DNS over TLS (DoT) offers encrypted DNS traffic, UUID-based tracking, and seamless integration into our DoH-based filtering engine—all without requiring an agent. It’s a strong choice for secure, stable DNS in trusted environments.

However, for mobile users, those relying on public networks, or those seeking maximum privacy, DNS over HTTPS (DoH) or the CyberFOX Agent may offer better resilience and control.