What action should be documented in the fire alarm logbook during a drill?

Documentation of the central station going online after a drill is essential as it indicates that the fire alarm system has reverted to its normal operational state post-drill. This action is crucial in maintaining a continuous and accurate record of the fire safety system's functionality and responsiveness during emergency scenarios. Properly logging this detail ensures that oversight entities can verify that the system was restored and is functioning effectively after the drill.

The other options, while they may hold significance in evaluating the effectiveness of the drill, do not directly pertain to the critical operational status of the fire alarm system following the completion of the exercise. Recording the central station's status provides a clear indication that all systems are operational and ready to respond to real emergencies, which is a primary focus of fire safety protocols.