PCA Prometheus Certified Associate

The Blackbox Exporter is the Prometheus component designed specifically for probing endpoints over various network protocols, including HTTP, HTTPS, TCP, ICMP, and DNS. It acts as a generic probe service, allowing Prometheus to test endpoints' availability, latency, and correctness without requiring instrumentation in the target application itself. For basic HTTP probing, the Blackbox Exporter performs HTTP GET or POST requests to defined URLs and exposes metrics like probe success, latency, response code, and SSL certificate validity. This makes it ideal for uptime and availability monitoring. By contrast, the JMX exporter is used for collecting metrics from Java applications, the Apache exporter for Apache HTTP Server metrics, and the SNMP exporter for network devices. Thus, only the Blackbox Exporter serves the purpose of HTTP probing. Reference: Verified from Prometheus documentation – Blackbox Exporter Overview and Exporter Usage Guidelines

In Prometheus best practices, high-cardinality labels—especially those containing unique or userspecific identifiers—should be avoided. The metric myapp_filG_uploads_total{userid="5123",status="failed"} exposes the userid as a label, which is problematic. Each distinct value of a label generates a new time series in Prometheus. If there are thousands or millions of unique users, this would exponentially increase the number of time series, leading to cardinality explosion, degraded performance, and high memory usage. The _total suffix is actually correct and required for counters, as per the Prometheus naming convention. The use of underscores in metric names is also correct, as Prometheus does not support dashes in metric identifiers. The status label, however, is perfectly valid because it typically has a low number of possible values (e.g., “success”, “failed”). Reference: Verified from Prometheus official documentation sectionsInstrumentation – Metric and Label Naming Best Practices and Writing Exporters.