The Overall System Health section in the Analysis Snapshot shows a list of all sites used by this test.
The performance evaluations are based on aggregated metrics as seen on all tests running at these sites, not just this particular test. Metrics are compared for the past hour relative to the past 24 hours.
This section shows whether the testing locations are experiencing global performance degradations across all tests running from that location. This helps indicate if the problem is isolated to the specific test, or if the problem may represent a larger more systematic problem affecting availability for all users from a specific ISP.