What is a disadvantage of centralized authentication?

What will be an ideal response?

In centralized authentication, the authentication server becomes a single point of failure. If that device fails or is compromised, the authentication process used for the entire organization will come to a standstill, and all information systems will become inoperable. This is a severe threat to the availability of these systems, when they are one glitch or one failed hard drive away from failure. An organization that uses this type of method must also have a contingency plan in place to get the server back online or provide alternative servers to limit the downtime a failure or compromise to this system would cause.