Question 3
ObservabilityWhat is the difference between the up metric automatically generated by Prometheus and application-specific health check metrics?
Correct answer: B
Explanation
Prometheus’s "up" metric shows whether the scrape succeeded, so it reflects target reachability and exporter response, not business logic. Application-specific health check metrics measure whether the app itself is functioning as intended, such as dependency checks or internal readiness, so they provide a deeper view of service health.
Why each option is right or wrong
A. up is a gauge, while health checks are counters.
B. up indicates scrape success; health checks indicate application functionality.
Prometheus’s built-in `up` time series is emitted per scrape target and is set to `1` when the scrape completes successfully and `0` when the scrape fails, so it only answers whether Prometheus could reach the endpoint and parse a response. By contrast, application health-check metrics are custom metrics exposed by the service itself and can encode internal readiness or dependency status, so they assess whether the application is actually functioning rather than merely being reachable.
C. up is only generated for Kubernetes Pods; health checks are for external services.
D. up requires custom instrumentation; health checks are built-in.
E. up triggers Alertmanager directly; health checks require PromQL rules.