PCA (Prometheus Certified Associate) sample exam question with answer 408

Question:
You are instrumenting your application for Prometheus. This application generates GitHub issues when an alert is received from Alertmanager. Sometimes however, an issue fails to be created.
You want to monitor the total number of issues that attempt to get created as well as the proportion of requests that succeed and the proportion that fail.
How should you BEST go about this?

1. Define a single summary metric that provides the total requests broken down by success and failure
2. Define two counter metrics, one for the total and the other for the failures. Calculate the number of successes as total - failures
3. Define three counter metrics, one for the total, one for the successes and one for the failures
4. Define a single histogram metric that provides the total requests broken down by success and failure

Answer:
B - is the correct answer
A - is incorrect as a summary is ideal for sampling observations. In this scenario we are better served by defining counters to represent the count of different types of requests
C - is incorrect as we only need two counters. The third can be derived through simple arithmetic using the values of the other two
D - is incorrect as a histogram is ideal for sampling observations. In this scenario we are better served by defining counters to represent the count of different types of requests