Generally, a drop ceiling implies a plenum, which is the technical term for the space above the drop ceiling. And generally, the plenum is how the air conditioning sucks the air out of the habitable space before heating or cooling it and returning it via ducts and vents.
The actual requirement is that a room dedicated to electrical or communications equipment must have fire stop walls, floors and ceiling rated for 2, 4, or 8 hours depending on some factors. Generally, the easiest way to do that is to make the walls of that room go all the way to the real ceiling.
And once your ceiling is that tall in such a small room, there's no need for a plenum and a drop ceiling is kind of pointless. You can directly vent with ducts and a fire damper to the adjacent plenum.