What is the port number for DNS?

DNS = port 53 (UDP for normal queries, TCP for zone transfers / large responses).

DNS = Port 53 (UDP and TCP)

DNS (Domain Name System) translates domain names to IP addresses.

Uses both UDP and TCP:

• UDP 53: Standard queries (most traffic)
• TCP 53: Zone transfers and large responses (>512 bytes)

Memory tip: DNS "goes" (5) to the "tree" (3) of domain names.

Go deeper:

• Domain Name System — Wikipedia overview confirming port 53 on UDP for queries and TCP for zone transfers.
• List of TCP and UDP port numbers — the broader lookup table placing 53 among the well-known ports.