When you run file transfer or Alibaba Cloud CDN (CDN) speed test tasks in Synthetic Monitoring, the Task Overview dashboard collects availability, download performance, and timing metrics from every monitoring point. Use the dashboard to compare download performance across cities and ISPs, isolate timing bottlenecks, and investigate errors.
Open the Task Overview dashboard
-
Log on to the ARMS console.
-
In the left-side navigation pane, choose Synthetic Monitoring > Scheduled Tests. On the Synthetic Tasks page, click the name of the task.
On the Synthetic Tasks page, click the name of a task.
Summary metrics
The top of the dashboard displays aggregate metrics for the selected time range.
| Metric | Description |
|---|---|
| Availability | Percentage of successful synthetic tests across all monitoring points. Availability = Successful tests / Total tests x 100%. A test is successful when it meets all assertion conditions. |
| Overall time | Total elapsed time from the start of DNS resolution to the completion of the file download. See the Timing breakdown section for the component phases that make up this metric. |
| Download speed | Average data transfer rate during the selected time range. Download speed = Downloaded bytes / Download duration. |
| Number of tests | Total synthetic tests executed in this task during the selected time range. |
| Number of errors | Synthetic tests that failed to meet the assertion conditions during the selected time range. |
Timing breakdown
Overall time is the sum of the following sequential phases. When a phase value appears unexpectedly high, investigate that phase to isolate the bottleneck.
| Phase | What it measures |
|---|---|
| DNS Time | Time spent on Alibaba Cloud DNS (DNS) resolution to resolve the domain name to an IP address. Not recorded when you use an IP address directly instead of a domain name, because no DNS resolution occurs. |
| Connection time | Time to establish a TCP connection with the target server. |
| SSL Usage | Time to complete the SSL/TLS handshake. Recorded only for HTTPS connections. The value is zero for HTTP connections because no handshake occurs. |
| Request sending time | Time to transmit the HTTP request to the server. |
| Waiting for response | Time between sending the request and receiving the first response byte (TTFB). |
| Download time | Time to download the complete response body. Larger response bodies typically produce higher values. |
Overall time = DNS Time + Connection time + SSL Usage + Request sending time + Waiting for response + Download time
SSL Usage is zero for HTTP connections. DNS Time is zero when the target is specified as an IP address.
City-level metrics
The City Dial Test Overview section breaks down performance metrics by city. Each row shows the following metrics for a single city:
| Metric | Description |
|---|---|
| Availability | Availability rate for the city. |
| Overall time | Total elapsed time from DNS resolution to download completion. |
| DNS Time | DNS resolution time. |
| Connection time | TCP connection time. |
| SSL Usage | SSL/TLS handshake time. |
| Request sending time | Request transmission time. |
| Waiting for response | Time to first byte (TTFB). |
| Download time | File download time. |
| Download speed | Average download speed. |
| Number of tests | Total synthetic tests initiated from the city. |
Compare rows to identify cities with degraded performance and determine which timing phase is responsible.
Trend charts
Availability trends
Tracks the availability rate over time. A sudden drop may indicate an outage or network issue at one or more monitoring points.
Time trend of each stage
Tracks each timing phase over time: Overall time, DNS Time, Connection time, SSL Usage, Request sending time, Waiting for response, Download time, and Download speed. Use these trends to identify which phase contributes most to performance changes over a given period.
Download time by city and ISP
| Chart | Description |
|---|---|
| Average download time (city) | Download time trends grouped by city. |
| Average download time (carrier) | Download time trends grouped by ISP. |
Download speed by city and ISP
| Chart | Description |
|---|---|
| Download Speed (city) | Download speed trends grouped by city. |
| Download speed (operator) | Download speed trends grouped by ISP. |
Top 5 rankings
These panels surface the worst-performing cities, ISPs, and error types so you can prioritize investigation.
| Panel | Description |
|---|---|
| The city's slowest Top5 | Five cities with the lowest average download speed. |
| Slowest operators Top5 | Five ISPs with the lowest average download speed. |
| Error Type Top5 | Five most frequent error types. |
Task analysis
For ad-hoc investigations beyond the predefined dashboard views, use task analysis. Task analysis combines custom filter conditions and aggregation dimensions to query all synthetic test data in real time. For more information, see Task analysis.