For a cloud-based system with an availability SLA of 99.99%, which unavailability time would be considered acceptable during a 30‑day test window?

For a cloud-based system with an availability SLA of 99.99%, which unavailability time would be considered acceptable during a 30‑day test window?

• A. 1 minute
• B. 4 minutes
• C. 10 minutes
• D. 60 minutes

Answer: (B)

An availability SLA of 99.99% means only a tiny amount of downtime is allowed over the test window. To see how much, convert the 30 days into minutes: 30 days × 24 hours × 60 minutes = 43,200 minutes. The allowed downtime is 0.01% of that, which is 0.0001 × 43,200 = 4.32 minutes. So, during a 30-day window, about 4.3 minutes of unavailability are permissible. Among the options, 4 minutes fits within this limit (it's under 4.32 minutes), while 10 minutes and 60 minutes exceed it. Although 1 minute would also be acceptable, the question aims for the maximum downtime still within the SLA, which is about 4 minutes.

An availability SLA of 99.99% means only a tiny amount of downtime is allowed over the test window. To see how much, convert the 30 days into minutes: 30 days × 24 hours × 60 minutes = 43,200 minutes. The allowed downtime is 0.01% of that, which is 0.0001 × 43,200 = 4.32 minutes. So, during a 30-day window, about 4.3 minutes of unavailability are permissible. Among the options, 4 minutes fits within this limit (it's under 4.32 minutes), while 10 minutes and 60 minutes exceed it. Although 1 minute would also be acceptable, the question aims for the maximum downtime still within the SLA, which is about 4 minutes.