What blackbox tells you
Synthetic and HTTP checks give the customer view and drive SLAs.
They catch DNS, TLS, and routing issues before internal metrics do.
What whitebox adds
Instrumentation shows why uptime is failing CPU, queues, DB saturation.
Use tracing to connect slow spans to failing endpoints.
Combine wisely
- Alert on blackbox first
- Use whitebox to triage
- Tie both to the same incident
Operate them together
Keep shared dashboards with both signal types.
Review which signals fired for each incident to tune coverage.
Neither works alone; customers only care about what they can reach.