Uptime Statistics

Detailed uptime calculation methodology and performance breakdown.

Uptime Calculation

Uptime is calculated as:

Uptime % = (Total Checks - Failed Checks) / Total Checks * 100

What Counts as a Failure

A check is counted as failed when:

• The HTTP status code does not match the expected status code
• The response validation fails
• The connection times out
• A network error occurs
• The TCP/UDP connection is refused

What Doesn’t Count

The following are excluded from uptime calculations:

• Paused periods - Time when the check is paused
• Smart verification passes - If the 30-second re-check succeeds, the initial failure is not counted
• Maintenance windows - Documented maintenance periods (if annotated)

Performance Breakdown

Each check captures detailed timing metrics:

DNS Lookup

Time to resolve the domain name to an IP address.

TCP Connect

Time to establish the TCP connection after DNS resolution.

TLS Handshake

Time to complete the TLS/SSL handshake (HTTPS only). Includes certificate verification.

Time to First Byte (TTFB)

Time from sending the request to receiving the first byte of the response. This is often the most meaningful metric for server-side performance.

Total Response Time

The complete end-to-end time: DNS + Connect + TLS + TTFB + Content Transfer.

Viewing Statistics

Per-Check Stats

Navigate to a check’s detail page to see its uptime statistics and performance breakdown.

Aggregated Stats

The dashboard provides an overview of uptime across all checks.

API Access

Access uptime statistics programmatically via the Check Stats API endpoint.

Best Practices

• Use TTFB as the primary metric for server-side performance
• Monitor DNS resolution time for CDN and DNS provider performance
• Track TLS handshake time to identify certificate issues
• Compare performance across regions to identify geographic bottlenecks