Which statement about availability is correct?

Which statement about availability is correct?

• A. Availability equals reliability only.
• B. Availability excludes maintainability.
• C. Availability considers reliability plus maintainability and uptime.
• D. Availability is unrelated to uptime.

Answer: (C)

Availability measures how ready a system is to perform its mission by accounting for both how often it works without failing and how quickly it can be restored when it does fail, along with the actual time it is up and running. In practice, that means availability combines reliability (the chance of operating without a failure) with maintainability (how fast you can fix it) and uptime (the amount of time the system is available to operate). That makes the statement that availability considers reliability plus maintainability and uptime the most accurate.

Think of it this way: a system might be highly reliable but if it takes a long time to repair, or if it’s rarely up and running due to long downtimes, its overall availability will be low. Conversely, quick repairs and lots of up time boost availability. The other options misstate one or more of those relationships and don’t reflect how uptime, reliability, and maintainability together determine readiness.