Which network term refers to the physical point where service begins?

The term that refers to the physical point where service begins is known as the Demarcation Point. This is a critical point in a telecommunications network that separates the service provider's responsibility from that of the customer. At this point, the service provider's equipment and wiring end, and the customer’s equipment begins.

Understanding the Demarcation Point is essential because it serves as a boundary for fault identification and responsibility. If an issue occurs beyond this point, the service provider typically is not responsible, while any problem before this point falls under their jurisdiction. This demarcation helps to clarify responsibilities concerning maintenance, troubleshooting, and service provisioning.

The other terms, while related to networking concepts, do not accurately define this physical point of service initiation. A Service Node generally refers to a device that handles particular services within a network, while a Connection Interface is more about the means by which devices connect within the network. Lastly, a Service Junction does not specifically refer to a point of service initiation in the same defined manner as the Demarcation Point does.