Exam Professional Cloud DevOps Engineer topic 1 question 167 discussion

C because you should set SLOs with some space between the current performance

C. Setting SLOs with reasonable headroom (190ms/330ms) above current performance (160ms/300ms) follows SRE best practices by providing operational flexibility while maintaining customer satisfaction.

B. 90th percentile - 160 ms, 95th percentile - 300 ms Why? SLOs Should Reflect Current User Happiness: Since customers are already satisfied with the current performance (90th @ 160ms, 95th @ 300ms), these values should be your baseline SLOs. Tightening the SLO (e.g., Option A) risks unnecessary breaches, while loosening it (e.g., Options C/D) reduces accountability. Google SRE Best Practices: SLOs should be based on historical data (here, 28-day measurements). Avoid overpromising (A) or undercommitting (C/D). Percentile Choice: The 90th/95th percentiles are standard for latency SLOs (captures "most users" without outliers dominating). Why Not the Others? A (Tighter SLOs): Unnecessary risk—why promise 150ms if users are happy with 160ms? C/D (Looser SLOs): Degrades trust—customers expect consistency, not regression.

The appropriate latency SLO to publish would be 90th percentile - 160 ms and 95th percentile - 300 ms, as these values reflect the current performance measurements over a 28-day window. These values are based on the actual data, and since customers are already happy with the application's performance and availability, it's reasonable to set the SLOs in line with the current performance metrics.

SLO should never be the same as current performance. You should always leave some room for error budget.

When setting up SLO based on SLI, there should be some margin, but not too much. Therefore C

C since B does not provide any error budget at all and D seem too relaxed

In B SLO makes sense because it pushes engineering teams to maintain strong performance. Then, a more relaxed SLA could be introduced to reduce financial risk, and so that consumers don´t assume current performance as the SLA.