Port 853: DNS over TLS
Port 853 is DNS over TLS, which encrypts DNS queries between a client and resolver to stop eavesdropping and tampering on the network path. It is the dedicated-port alternative to DNS over HTTPS, which instead shares port 443.
TCPCore services EncryptedIANA assigned
| Port number | 853 |
|---|---|
| Service | DNS over TLS (DoT) |
| Protocol | TCP |
| Category | Core services |
| Default encryption | Yes (TLS/SSH) |
Frequently asked questions
What is port 853 used for?
Port 853 is DNS over TLS, which encrypts DNS queries between a client and resolver to stop eavesdropping and tampering on the network path. It is the dedicated-port alternative to DNS over HTTPS, which instead shares port 443.
Is port 853 TCP or UDP?
Port 853 (DNS over TLS) uses TCP.
Is port 853 secure?
Yes. Port 853 carries encrypted traffic by default, so data in transit is protected.
Should I open port 853 on my firewall?
Only if you specifically need DNS over TLS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.