What is the purpose of port numbers in the Transport Layer?

The purpose of port numbers in the Transport Layer is primarily to identify processes and services on a network. Each port number serves as a unique identifier for specific applications or services running on a device, which allows the Transport Layer protocols (such as TCP and UDP) to distinguish between multiple services communicating over the same network connection.

When data packets are transmitted across a network, the Transport Layer encapsulates these packets with header information, including the source and destination port numbers. This is crucial for directing incoming traffic to the correct application on a server or client. For instance, a web server typically listens on port 80 for HTTP traffic, while an email server might listen on port 25 for SMTP traffic. This differentiation enables multiple services to run concurrently on the same physical network connection without conflict.

In contrast, other options refer to different aspects of networking that do not directly relate to what port numbers do. For example, controlling access to network resources pertains to security measures like authentication and authorization; encrypting data packets involves cryptographic protocols, and managing device connections relates more to the physical or link layers of networking rather than the Transport Layer's function of handling communication between processes. Thus, identifying processes and services is the most accurate representation of the role of port numbers in the Transport