What term describes the port from which application traffic originates?

• A. Source port
• B. Destination port
• C. IP address
• D. Subnet mask

Answer: (A)

In TCP/UDP communications, each packet carries two port numbers: a source port and a destination port. The port number at the sending end identifies the application or process that generated the traffic, and it is typically an ephemeral, short‑lived port chosen by the client. The port number at the receiving end identifies the service on the destination host that will handle the traffic.

Therefore, the term that describes the port from which application traffic originates is the source port. The destination port is the service port on the recipient, IP address is the host’s address, and the subnet mask is used for determining the network portion of an IP address.