What is a disadvantage to using a master key system?

• A. Increases security risk if the master key is exposed
• B. Requires specialized maintenance routines
• C. The cost to re-key all of the locks in the system
• D. Adds unnecessary complexity to access control

Answer: (C)

Master key systems trade convenience for cost. They let one key operate many locks, reducing the number of keys you have to manage, but when access needs to change or a key is lost, you don’t just rekey a single lock—you often have to rekey every lock in the affected portion of the system to invalidate old keys and preserve the hierarchy. That re-keying work across many locks adds up in labor, time, and materials, making it a substantial disadvantage of this approach.

While a compromised master key is a real security risk and maintenance can be more involved than for a simple system, the most immediate, tangible downside highlighted here is the cost and effort required to re-key all the locks in the system.