What is DNS over TLS DoT?

Understanding DNS over TLS DoT

DNS over TLS (DoT) solves a fundamental privacy problem with traditional DNS—that queries and responses are transmitted in plaintext, allowing anyone with access to the network path to monitor which websites are being visited. DoT encrypts DNS communications using the Transport Layer Security protocol on a dedicated port (853), preventing such surveillance while maintaining the integrity of responses. While similar in goal to DNS over HTTPS (DoH), DoT uses a separate port rather than blending with web traffic, making it easier for network administrators to manage specifically as a DNS service. Organizations implementing DoT must configure compatible DNS resolvers, potentially establish internal trusted resolvers for enterprise environments, and consider how encrypted DNS interacts with security monitoring tools that previously relied on inspecting plaintext queries. Effective deployment typically balances privacy benefits against operational requirements like split-horizon DNS for internal resources. While DoT adoption has been slower than DoH due to less direct support in browsers, it remains an important option for organizations seeking to encrypt DNS traffic while maintaining traditional network architecture.