Application protocols connect the client and server by using which mechanism?

Application protocols connect the client and server by using which mechanism?

• A. A dedicated physical channel per session.
• B. A TCP or UDP port.
• C. A direct socket file path.
• D. A hardware MAC address mapping.

Answer: (B)

Ports. Application protocols connect clients and servers by using port numbers at the transport layer (TCP or UDP). A port identifies which specific service or process on a host should handle the data, allowing multiple services to run on the same IP address without collision. The transport layer uses these ports to direct traffic to the right socket, enabling either a reliable connection (TCP) or simple datagrams (UDP). Why the others don’t fit: a dedicated physical channel per session isn’t how modern networks operate—many connections share the same physical medium, with logical connections established by the transport protocol. A direct socket file path is used for local inter-process communication on the same machine, not for networked client–server connections. A hardware MAC address mapping is about local network addressing at the data link layer, not how application protocols establish connections across networks.

Ports. Application protocols connect clients and servers by using port numbers at the transport layer (TCP or UDP). A port identifies which specific service or process on a host should handle the data, allowing multiple services to run on the same IP address without collision. The transport layer uses these ports to direct traffic to the right socket, enabling either a reliable connection (TCP) or simple datagrams (UDP).

Why the others don’t fit: a dedicated physical channel per session isn’t how modern networks operate—many connections share the same physical medium, with logical connections established by the transport protocol. A direct socket file path is used for local inter-process communication on the same machine, not for networked client–server connections. A hardware MAC address mapping is about local network addressing at the data link layer, not how application protocols establish connections across networks.