Which principle ensures data is accessible when needed?

• A. Confidentiality
• B. Integrity
• C. Availability
• D. Authentication

Answer: (C)

Availability is the principle that ensures data and systems are accessible to authorized users whenever they need them. It focuses on uptime, quick access, and resilience, using measures like redundant hardware, backups, failover mechanisms, and disaster recovery plans to keep services reachable even during outages or attacks. When someone needs to work, they should be able to reach the system and retrieve data without unnecessary delay, which is what availability guarantees.

Confidentiality protects data from being exposed to unauthorized parties, integrity ensures data isn’t altered or corrupted, and authentication verifies who is requesting access. These are important, but they don’t by themselves ensure that data remains accessible when needed—that role belongs to availability.