PCA (Prometheus Certified Associate) sample exam question with answer 41

Question:
Regarding histogram and summary metrics, which of the following is true?

1. Summary metrics are evaluated on the server side
2. Histogram metrics generally cannot be aggregated
3. Summary metrics generally cannot be aggregated
4. Histogram metrics are evaluated on the client side

Answer:
C - Summary metrics generally cannot be aggregated.
Since histograms provided bucketed observations they can be aggregated via PromQL.
Histogram quantiles are calculated on the server side via PromQL
Summary quantiles are evaluated on the client side by the instrumented application.
More information on histograms and summaries