DNS (Domain Name System) uses port 53.
That is, DNS primarily operates on port 53 for both UDP and TCP protocols. UDP is generally used for standard DNS queries because it's faster and connectionless. TCP is used when the response data size exceeds the UDP limit (typically 512 bytes) or for zone transfers between DNS servers.
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UDP Port 53: Used for most DNS queries. The client sends a query to the DNS server on port 53 using UDP.
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TCP Port 53: Used for:
- Zone transfers between DNS servers.
- Queries where the response size exceeds the UDP limit (usually 512 bytes). In this case, the DNS server will truncate the UDP response and indicate that the client should retry using TCP.
While DNS configuration is optional in many network settings (as the provided reference suggests, in specific device setups), the use of port 53 is fundamental to the DNS protocol itself. If you're configuring a device to use a DNS server, you generally only need to specify the DNS server's IP address. The device will automatically communicate with the DNS server on port 53.
