Port 53 — DNS
Quick reference for TCP/UDP port 53, used by DNS. Includes what the service does, security guidance and related ports.
What is port 53?
Domain Name System lookups.
What port does DNS use?
DNS listens on port 53 by default.
Is port 53 open? How to check
Run one of these from your computer, replacing HOST with the IP address or domain you want to test.
nc -zv HOST 53
Test-NetConnection HOST -Port 53
nmap -p 53 HOST
A refused or timed-out connection means the port is closed or filtered by a firewall.
Security guidance
Low risk — designed for public exposure
Port 53 (DNS) is designed for public exposure. Standard hardening (TLS certs, current firmware, sensible rate limits) is enough — no special isolation needed.
Related ports
Frequently asked
What is port 53 used for?+
Port 53 is the standard TCP/UDP port for DNS. Domain Name System lookups.
What port does DNS use?+
DNS listens on port 53 by default.
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