Which is a key feature of the HDLC protocol's operation?

The key feature of the HDLC (High-Level Data Link Control) protocol is that it can only send frames to one specific destination. HDLC is a point-to-point protocol, which means it establishes a direct connection between two devices for communication. This is fundamental to how HDLC operates, as it encapsulates data into frames and establishes a dedicated link for the transmission between two endpoints.

The implication of this feature is that since HDLC is designed for point-to-point connections, it does not support broadcasting or multicasting to multiple destinations at the same time. Instead, the protocol is structured to ensure reliable communication between just two devices, making it efficient for scenarios where a dedicated communication line is needed.

In contrast, the other features mentioned do not accurately represent how HDLC functions. For instance, while HDLC can operate without necessarily embedding an address field in its frames for identification (which can vary based on the context of connection), it typically does require some addressing mechanism to differentiate between connections in multi-link environments despite its point-to-point nature. Error checking is indeed part of HDLC's capabilities, but it involves checksums as well, which are more sophisticated than basic error checking alone.