What is the function of ephemeral port numbers?

Ephemeral port numbers are utilized to establish temporary communication channels between devices during a network session. When a client device initiates a connection to a server, it typically uses an ephemeral port number to identify the specific session on its side. This allows for multiple sessions to occur simultaneously without interference, as each session can be differentiated by its unique port number.

The nature of these ports being "ephemeral" or temporary is essential for dynamic network applications where multiple connections may be established and terminated frequently. This characteristic enables efficient use of network resources and helps manage connections effectively.

The other options do not accurately describe ephemeral port numbers' function. Permanent server applications typically use well-known, static port numbers to ensure reliable access; static connections are usually defined by fixed port assignments, and protocol services are associated with those well-known ports, rather than ephemeral ones which are dynamic.