CompTIA Server+ (SK0-005)Server Hardware Installation and ManagementEasy
A technician is installing a new server that is 3U in height into a 42U rack. The rack already contains equipment occupying 27U of contiguous space from the bottom. After the new server is installed, how many rack units of open space remain in the rack?
- A15U
- B18U
- C12U
- D9U
Show answer & explanationAnswer & explanation
Correct answer: C. 12U
The rack has 42U total minus 27U already used, leaving 15U free before the install. Installing the 3U server uses 3 more units, leaving 15U - 3U = 12U of open space.
Why the other options are wrong
- A. This is the space available before the new server was installed, not after.
- B. Overstates remaining space; does not account for the new server's height.
- D. Incorrect subtraction; does not match 15U-3U.
Rack Unit (U) Sizing
A rack unit (U) equals 1.75 inches of vertical rack space; server and equipment heights are measured in U to determine rack capacity.
- 1U = 1.75 inches (4.45 cm)
- Standard racks are commonly 42U in height
- Available space = total U minus U already occupied
Memory trick: Each U is a 1.75-inch slice of the rack sandwich.