In cloud observability, which combination of artifacts constitutes the three pillars used to understand system state?

• A. Logs
• B. Metrics
• C. Traces
• D. Logs, metrics, and traces

Answer: (D)

In cloud observability, understanding system state comes from three kinds of telemetry: logs, metrics, and traces. Metrics give quantifiable signals about how the system behaves over time—things like request rate, error rate, and latency. They let you see trends, set baselines, and spot anomalies at a glance. Logs capture discrete events with timestamps and rich context, providing the detailed evidence you can search through to diagnose exactly what happened. Traces map the path of a single request as it flows through multiple services, showing where time is spent and where bottlenecks occur in the end-to-end path.

When you combine all three, you get a complete picture: metrics give the health overview and trends, traces reveal the end-to-end performance and pinpoint where delays arise, and logs offer the in-depth, contextual information needed to diagnose root causes. Relying on only one or two of these artifacts leaves gaps—without metrics you miss the big picture, without traces you can’t see cross-service flows, and without logs you lose the detailed evidence. Therefore, the three pillars are logs, metrics, and traces.