What is the well-known port range according to IANA?

The well-known port range defined by the Internet Assigned Numbers Authority (IANA) is from 0 to 1023. This range is reserved for specific protocols and services, allowing them to operate without conflicting with user-defined applications. For instance, common services such as HTTP (port 80), FTP (port 21), and SMTP (port 25) utilize ports in this range. These ports are standardized across the internet to ensure consistent communication between various systems and applications, making them essential for the functionality of web, email, and file transfer services.

In contrast, the other ranges mentioned in the choices are categorized differently. The range from 1024 to 49151 is classified as the registered ports, which are used by software applications that are not as universally recognized as those using the well-known ports. The highest range, 49152 to 65535, is known as dynamic or private ports, which are typically assigned dynamically by applications when a connection is established. Lastly, the range from 65536 to 100000 does not exist within the current port numbering system as defined by IANA, which creates confusion for anyone referencing standard ports.