1. Uptime Monitoring Checks

DownXmonitor operates a background monitoring process that sequentially validates each service's health on a 60-second cycle. For each check, the engine performs the following actions:

• DNS Resolution: Validates that the hostname resolves to one or more IPv4/IPv6 addresses.
• TCP Connection Handshake: Initiates a connection on port 80 (HTTP) or 443 (HTTPS) to verify server responsiveness.
• TLS Handshake: For secure sites, completes a TLS handshake and verifies SSL certificate validity.
• HTTP Request: Sends a standard GET/HEAD request using a customized browser User-Agent header and registers the returned HTTP status code (e.g. `200 OK`).

2. Defining Service Status

We classify services into three states:

• Up (Active): The server responds successfully with a status code in the 2xx or 3xx range, and the connection completes within 1.5 seconds.
• Slow: The server responds successfully, but the overall round-trip response time exceeds 1.5 seconds.
• Down (Outage): The server fails to respond, returns a server error code (5xx), refuses the connection, or times out (exceeds 5.0 seconds).

3. Outage Report Verification

To prevent malicious users from spamming reports and showing false outages on competitor domains, we implement rate limits and verification rules:

• IP Cooldown: An IP address is limited to one report per service every 15 minutes.
• Spam Thresholds: Real-time charts require multiple independent reports from distinct networks within a rolling window before triggering outage warnings.

4. Uptime Percentage Calculation

The 24-hour uptime percentage displayed on the dashboard and status pages is calculated as follows:

Uptime % = (Successful Checks / Total Checks in 24h) * 100

Any check resulting in a "Down" state registers a 0ms ping value and is factored in as downtime, reducing the rolling 24-hour uptime percentage.