What is the general rule when it comes to upgrading operating systems on commercial servers?

A.
Do not perform an upgrade if nothing is broken.

B.
Perform an upgrade if something is broken.

C.
Always perform an upgrade to add all new features.

D.
None of the above.

Explanation:
The general rule when it comes to upgrading operating systems on commercial servers is: Do not perform an upgrade if nothing is broken. When an upgrade becomes available, you should carefully consider the implications of performing the upgrade. If the system is performing as expected, is stable, and all tasks are being completed, you should generally not perform any upgrade to the OS.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 428-429.