Secure DNS primarily uses port 853.
When implementing secure DNS, specifically DNS over TLS (DoT), the standard port used is 853. This port ensures that DNS queries and responses are encrypted, protecting them from eavesdropping and manipulation. If a client cannot establish a secure connection on port 853, it might fall back to the standard, less secure DNS port 53, which uses UDP or TCP without encryption. Therefore, for secure DNS communication, configuring and utilizing port 853 is essential.
