Synthetic Monitoring Metrics Glossary
Who it's for: Anyone interpreting synthetic dashboards, alerts, or reports.
You’ll learn: Definitions for each metric, when to use them, and how they influence performance analysis.
Execution Summary
- Total Runs – Count of times the test executed during the selected window.
- Pass/Fail Ratio – Percentage split of successful versus failed runs.
- Average Duration – Mean completion time for the full journey.
- Run Locations – Geographic regions that executed the journey.
Request-Based Metrics
- Total Requests – Number of responses collected across all steps.
- 200 Responses – Successful requests.
- 300 Responses – Redirects; frequent redirects may indicate inefficient routing.
- 400 Responses – Client-side errors (e.g., 404, 401). Watch for broken assets or auth issues.
- 500 Responses – Server-side failures; often surface infrastructure outages.
- Blocked Requests – Assets intentionally blocked by your journey configuration.
Timing Metrics
- Total Response Time – Sum of network and server processing times for the request.
- DNS Time – Time to resolve the domain name. High values hint at DNS provider issues.
- Connect Time – Time spent establishing the TCP connection.
- SSL Time – Duration of the TLS handshake.
- Send Time – Time taken to send the request payload.
- Wait Time (TTFB) – Time waiting for the first byte of the response; sensitive to application performance.
- Receive Time – Duration to download the response body.
Resource Classification
- JavaScript (JS) – Script files executed. Track spikes to catch bundle regressions.
- CSS – Stylesheet requests; missing CSS may break layout and cause failures.
- Images (IMG) – Images loaded during the journey.
- Fonts – Web fonts fetched; useful for brand consistency checks.
- Media – Video or audio streams triggered in the journey.
- Fetch / XHR – API calls executed within the page. Monitor for auth breaks or slow third-party services.
Error Insights
- Console Errors – JavaScript errors thrown during execution.
- Console Warnings – Non-blocking issues (deprecated APIs, missing assets).
- Assertion Failures – Custom checks you add in your journey (e.g., element visibility, text value mismatches).
- Security Flags – Events such as mixed content, HSTS disabled, or certificate anomalies.
Quality Signals
- Screenshots Captured – Images stored per run for visual validation.
- Video Recording – Playback length of the run, useful for step-by-step reviews.
- Lighthouse Scores – Automated Web Vitals across Performance, Accessibility, SEO, and Best Practices.
📌 Use these metrics to analyze performance and detect issues proactively. Compare across locations and time ranges to isolate regressions.
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