Standard zone

From Ultipedia

Standard Zone defense (aka '3-3-1' or often just plain 'zone') is the most commonly played zone defense. It involves the three most downfield players forming a cup, with three mids spread across the field, a deep defender coordinating the defense.

Note that in some circles this zone is historically referred to as '2-3-2' with the belief that the top of the cup is a mid position, and the mid mid plays far enough back to be considered a deep.