Which of the following is NOT a common control used to protect the availability of information?

The focus of this question is on identifying controls specifically designed to protect the availability of information. Availability ensures that information and resources are accessible to authorized users when needed.

Redundancy is a common strategy employed to enhance availability. It involves duplicating critical components or systems so that if one fails, the other can take over, minimizing downtime. Backups are also vital for availability, as they ensure data can be restored in case of loss or corruption, thus maintaining access to information.

Access controls are important for protecting the integrity and confidentiality of information but do not directly impact availability. Their primary role is to restrict unauthorized access, which does not necessarily enhance the accessibility of information itself.

Encryption, while essential for protecting the confidentiality of data, does not relate to availability. Encrypting data does not ensure that it remains accessible to users; instead, it may even complicate access if the decryption keys are not available. Hence, it does not serve as a direct control for maintaining information availability. This is why encryption is identified as the option that does not contribute to the protection of availability.