PCA (Prometheus Certified Associate) sample exam question with answer 474

Question:
What is the difference between a histogram and a summary metric in Prometheus?

1. Histograms are used to calculate configurable quantiles over a sliding time window, while summaries are used to count the number of times an event occurs
2. Histograms and summaries are the same type of metric
3. Histograms provide a sum of all observed values and count them in configurable buckets, while summaries calculate configurable quantiles over a sliding time window and provide a total count of observations and a sum of all observed values
4. Summaries are used to calculate Apdex scores, while histograms are used to count the number of times an event occurs

Answer:
C - is correct answer. Histograms and summaries are both used to sample observations and provide a total count of observations and a sum of all observed values. However, histograms count observations in configurable buckets, while summaries calculate configurable quantiles over a sliding time window