Which organization is responsible for listing port assignments?

The organization responsible for listing port assignments is the Internet Assigned Numbers Authority, commonly known as IANA. IANA maintains the official registry for assigned protocol numbers, including port numbers that are used for network communication. This resource is crucial for ensuring that various services can communicate effectively over the internet, as different services, applications, and protocols use specific port numbers to avoid conflicts and to facilitate organized traffic routing.

The other organizations mentioned have different roles. For instance, ISSA, or the Information Systems Security Association, focuses on global information security networking and education, which does not involve port assignments. Network Solutions is a commercial service provider that primarily focuses on domain registration and web hosting rather than protocol or port assignment. InterNIC, once a significant player in domain registration, is no longer the primary authority over port assignments as its functions primarily shifted with the evolution of domain registration and maintenance. Thus, IANA stands out as the correct organization for this purpose.