The DNS Protocol - Part 1: Introduction - firewall.cx
https://www.firewall.cx/networking/network-protocols/dns-protocol/protocols-dns.html
WEB2 days ago · The DNS protocol utilises Port 53 for its service. This means that a DNS server listens on Port 53 and expects any client wishing to use the service to use the same port. There are, however, cases where you might need to use a different port, something possible depending on the operating system and DNS server you are running.
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