The period of time when a communication network becomes inoperative, is…

In networking and systems terminology, a network's or system's operational status over time is described using two complementary terms: "Uptime" is the period during which the network or service functions normally and is available for use, while "Downtime" is the complementary period during which it is unavailable or fails to function as intended, due to failure, maintenance, or an outage.

The question asks specifically for the term describing the period when a communication network becomes inoperative, i.e., stops functioning. This matches the definition of downtime exactly.

• "Uptime" describes the opposite scenario — the network being operational and available, not inoperative.

• "Time fit" is not a recognized networking or systems term.

• "Loadtime" describes how long content or a system takes to load, not a state of failure or unavailability.

Therefore, "Downtime" is the correct term for the period when a communication network becomes inoperative.