PROFESSIONAL-CLOUD-DEVOPS-ENGINEER Question #125: Real Exam Question with Answer & Explanation

Question

You support a high-traffic web application and want to ensure that the home page loads in a timely manner. As a first step, you decide to implement a Service Level Indicator (SLI) to represent home page request latency with an acceptable page load time set to 100 ms. What is the Google-recommended way of calculating this SLI?

Options

• ABucketize the request latencies into ranges, and then compute the percentile at 100 ms.
• BBucketize the request latencies into ranges, and then compute the median and 90th percentiles.
• CCount the number of home page requests that load in under 100 ms, and then divide by the total
• DCount the number of home page request that load in under 100 ms, and then divide by the total

Explanation

Google recommends defining SLIs as a ratio of 'good events' to total events. For latency, a 'good event' is a request that completes within the acceptable threshold (100 ms). The SLI is therefore: (number of requests completing under 100 ms) / (total number of requests). This produces a proportion between 0 and 1 that is easy to track against an SLO. Options A and B describe distribution/percentile analysis, which are useful for investigation but not the recommended SLI formula. Option D is a duplicate of C with a typo and is the distractor - C is the correctly worded answer.

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