CompTIA Security+ (SY0-701)Security Program Management and OversightMedium
A cloud hosting provider's contract guarantees 99.9% uptime per year. Based on this guarantee, approximately how much total downtime is contractually permitted in a single year (365 days) before the provider is in breach?
- A8.76 hours
- B4.38 hours
- C87.6 hours
- D36.5 hours
Show answer & explanationAnswer & explanation
Correct answer: A. 8.76 hours
A year has 8,760 hours (365 days x 24 hours). Allowed downtime = 8,760 x (1 - 0.999) = 8,760 x 0.001 = 8.76 hours per year.
Why the other options are wrong
- B. This is half of the correct value, not derived from the given percentage.
- C. This would be the result of using 99% uptime instead of 99.9%.
- D. This does not correspond to the correct percentage calculation.
SLA Uptime Calculation
A Service Level Agreement (SLA) specifies a guaranteed availability percentage; allowed downtime is calculated as total time multiplied by (1 - availability).
- Total hours in a year = 8,760
- 99.9% uptime allows ~8.76 hours downtime/year
- Higher 'nines' of availability mean exponentially less allowed downtime
Memory trick: Each extra 'nine' shrinks downtime by 10x — the Rule of Nines.