Master streams are most commonly used for __________ attack.

Master streams are most commonly used for defensive attacks due to their ability to deliver large volumes of water effectively over significant distances. This capability is crucial when a structure is fully involved in fire or when the fire poses a threat to adjacent structures. Utilizing a master stream allows firefighters to apply water from a distance, thereby increasing safety for personnel while still addressing the fire's intensity.

In defensive operations, the goal is often to protect exposures or to control the fire's spread without necessarily entering the structure. Master streams excel in these situations, as they can quickly suppress flames and reduce the heat buildup, giving crews time to evaluate the scene and formulate an action plan. Their high flow rates are also beneficial in rapidly cooling large areas and preventing the fire from rekindling.