Which application is associated with the well-known port number 53?

Port number 53 is specifically designated for the Domain Name Service (DNS), which is a critical component of the internet's architecture. DNS is responsible for translating user-friendly domain names (such as www.example.com) into IP addresses (such as 192.0.2.1) that computers use to identify each other on the network. This translation is essential for enabling users to easily access websites and services over the internet.

When a device makes a request to access a specific website, it contacts a DNS server using port 53 to resolve the domain name into the corresponding IP address. Without DNS functioning over this designated port, navigating to a website would require users to remember complex numerical IP addresses instead of simpler domain names, making internet usage significantly more cumbersome.

This use of port 53 for DNS is standardized and well-documented, highlighting its foundational role in network operations and the seamless experience of browsing the web.