53 DNSDomain Name System name resolution. UDP for queries, TCP for zone transfers and large responses.
Open both transports. UDP/53 for lookups; TCP/53 for AXFR/IXFR and EDNS responses over 512 bytes.
| Transport | Status | Meaning |
|---|---|---|
| TCP | Yes | Assigned by IANA and standardized, specified, or widely used on this port. |
| UDP | Yes | Assigned by IANA and standardized, specified, or widely used on this port. |
| SCTP | — | Not applicable for this transport. |
| DCCP | — | Not applicable for this transport. |
Well-known (0–1023). System port for a core service. On Unix-like systems, binding it requires superuser privileges.
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