Port 53: DNS
Port 53 is DNS, which resolves names like example.com into IP addresses. Most lookups use UDP; TCP is used for zone transfers and large responses that do not fit in a single UDP packet.
TCP/UDPCore servicesUnencrypted by defaultIANA assigned
| Port number | 53 |
|---|---|
| Service | Domain Name System |
| Protocol | TCP/UDP |
| Category | Core services |
| Default encryption | No |
Security note. Port 53 is not encrypted by default. Restrict it to trusted networks, or use an encrypted alternative where one exists, to avoid exposing credentials and data in transit.
Frequently asked questions
What is port 53 used for?
Port 53 is DNS, which resolves names like example.com into IP addresses. Most lookups use UDP; TCP is used for zone transfers and large responses that do not fit in a single UDP packet.
Is port 53 TCP or UDP?
Port 53 (DNS) uses TCP/UDP.
Is port 53 secure?
Port 53 is not encrypted by default. Where possible, use an encrypted alternative or tunnel it over TLS or a VPN.
Should I open port 53 on my firewall?
Only if you specifically need DNS. Expose it to the smallest set of trusted sources, and never open database or Windows-service ports to the whole internet.