Prometheus & Pull Model — KCNA Practice Question
A representative Kubernetes and Cloud Native Associate (KCNA) exam question on Prometheus & Pull Model. Work through it below, then read why each option is right or wrong.
This question is part of the free Kubernetes and Cloud Native Associate practice test.
Short answer
The correct answer is A. The last scrape of that instance failed, so Prometheus could not reach the pod's metrics endpoint..
A is correct. Prometheus stores up as 1 when an instance is reachable and 0 when the scrape failed. Prometheus pulls metrics from targets, so the value describes the scrape itself. B is wrong because Prometheus pulls metrics over HTTP and the pod does not push this value. C is wrong because a zero value of up says nothing about counter values; it only reports scrape success. D is wrong because silences are an Alertmanager feature and do not change the up series.
The Question
Prometheus scrapes a web application every 30 seconds. For one pod, the series up{job="web", instance="10.0.3.7:8080"} now has the value 0, while the other pods show 1. What does this value mean?
Why A is correct
A is correct. Prometheus stores up as 1 when an instance is reachable and 0 when the scrape failed. Prometheus pulls metrics from targets, so the value describes the scrape itself. B is wrong because Prometheus pulls metrics over HTTP and the pod does not push this value. C is wrong because a zero value of up says nothing about counter values; it only reports scrape success. D is wrong because silences are an Alertmanager feature and do not change the up series.
Why the other options are wrong
Option B does not satisfy the requirement in the scenario. Review the explanation above: the correct choice (A) is the only one that fully meets every constraint stated in the question.
Option C does not satisfy the requirement in the scenario. Review the explanation above: the correct choice (A) is the only one that fully meets every constraint stated in the question.
Option D does not satisfy the requirement in the scenario. Review the explanation above: the correct choice (A) is the only one that fully meets every constraint stated in the question.
Key idea: Prometheus & Pull Model
A is correct. Prometheus stores up as 1 when an instance is reachable and 0 when the scrape failed. Prometheus pulls metrics from targets, so the value describes the scrape itself. B is wrong because Prometheus pulls metrics over HTTP and the pod does not push this value. C is wrong because a zero value of up says nothing about counter values; it only reports scrape success. D is wrong because silences are an Alertmanager feature and do not change the up series. On the KCNA exam, questions in the "Cloud Native Architecture" domain test whether you can map a scenario's constraints to the right choice. Read the requirement carefully, eliminate options that violate any single constraint, and pick the one that satisfies all of them with the least operational overhead.
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