Uptime Monitoring

Available on: Free Plus Pro Elite

1. What This Feature Does

Uptime Monitoring tracks whether the hosts behind your DDNS domains are reachable. The system periodically checks connectivity to the target IP address, records response times in milliseconds, and calculates uptime percentages over 24-hour, 7-day, and 30-day windows. Each domain has monitoring individually enabled or disabled via a toggle in the domain list.

Monitoring data is stored in two layers: real-time status and recent checks in Redis, and daily aggregates in PostgreSQL. The 24-hour uptime percentage is computed from hourly check data in Redis, while 7-day and 30-day uptime percentages are derived from daily aggregates in the database.

2. When You Should Use It

• You host a service on a dynamic IP and need to track whether it remains reachable after IP updates.
• You manage multiple servers or home labs and want centralized uptime visibility for all your DDNS domains.
• You need historical uptime data to demonstrate service reliability or troubleshoot intermittent outages.
• You want to detect when a host goes offline without manually checking each endpoint.

3. When You Should Not Use It

• Complex health checks: Uptime monitoring performs simple connectivity checks. It does not validate HTTP status codes, SSL certificates, or application-level responses. For detailed service monitoring, use a dedicated monitoring service.
• Domains without IPs: Monitoring a domain that has no IP address assigned will run but cannot perform connectivity checks. Assign an IP first.
• Plan limits reached: If you have enabled monitoring on the maximum number of domains for your plan (5 on Free, 50 on Pro, 500 on Elite), you cannot enable monitoring on additional domains until you disable it on existing ones or upgrade.
• Real-time alerting: Uptime monitoring does not send notifications when a domain goes down. It provides historical data and current status only.

4. Prerequisites

• At least one DDNS domain created in your account.
• The domain should have a valid IP address assigned for meaningful monitoring results.
• Monitoring capacity available in your plan: Free (5 monitored domains), Pro (50 monitored domains), Elite (500 monitored domains).
• API access (for programmatic control): requires Plus plan or higher.

5. How It Works (Brief)

When monitoring is enabled for a domain, the system performs periodic connectivity checks to the domain's current IP address. Each check records the timestamp, whether the host was reachable, the response time in milliseconds, and any error encountered. Hourly statistics are stored in Redis under keys uptime:stats:{domain_id}:{YYYYMMDDHH} and aggregated daily into the PostgreSQL uptime_daily table.

The dashboard and API endpoints compute uptime percentages by dividing successful checks by total checks within each time window. The 24-hour percentage uses hourly Redis data, while 7-day and 30-day percentages query daily aggregates from the database. Current status (is_up and current_status) reflects the most recent check result stored in uptime:domain:{domain_id}.

6. How to Use It

Enabling monitoring for a domain

1. Navigate to Dashboard > Domains.
2. In the domain table, locate the domain you want to monitor.
3. In the Monitoring column, click the gray monitor-off icon.
4. The icon changes to green, indicating monitoring is now enabled.
5. If you have reached your plan's monitoring limit, a message appears stating "Monitoring limit reached for your plan."

Disabling monitoring for a domain

1. In the domain table, locate the domain with monitoring enabled.
2. Click the green monitor icon in the Monitoring column.
3. The icon changes to gray, and monitoring stops. Historical data is retained but no new checks are performed.

Viewing uptime data

1. Navigate to Dashboard > Uptime to see the uptime dashboard overview.
2. The overview displays:
   • Overall uptime percentage for 24 hours, 7 days, and 30 days.
   • Total number of domains monitored.
   • Count of domains currently up and currently down.
   • Average response time in milliseconds across all monitored domains.
3. To view detailed data for a specific domain, click the domain name in the list or use the API endpoint GET /uptime/domain/{domain_id}.

Enabling monitoring via API

Use the following endpoint to toggle monitoring:

POST /uptime/domain/{domain_id}/monitor
Content-Type: application/json

{
  "enabled": true
}

Response:

{
  "success": true,
  "monitor_enabled": true,
  "domain_id": 123,
  "fqdn": "myserver.certadns.com"
}

7. Inputs and Settings

Setting	Description	Values
Monitor Enabled	Whether uptime monitoring is active for the domain.	Boolean: true (enabled) or false (disabled). Toggled via UI or API.
Domain ID	Internal identifier for the domain being monitored.	Integer. Required when calling API endpoints.

No additional configuration is required. Check frequency and timeout values are managed system-wide and are not user-configurable.

8. Outputs and Results

Dashboard overview metrics

The uptime dashboard (GET /uptime/dashboard) returns the following fields:

Field	Description
overall_uptime_24h	Uptime percentage across all monitored domains in the past 24 hours.
overall_uptime_7d	Uptime percentage across all monitored domains in the past 7 days.
overall_uptime_30d	Uptime percentage across all monitored domains in the past 30 days.
domains_monitored	Total count of domains with monitoring enabled.
domains_up	Count of monitored domains currently reachable.
domains_down	Count of monitored domains currently unreachable.
average_response_time_ms	Average response time in milliseconds for the most recent check across all monitored domains.

Per-domain uptime data

The domain detail endpoint (GET /uptime/domain/{domain_id}) returns:

Field	Description
domain_id	Internal ID of the domain.
fqdn	Fully qualified domain name.
is_up	Boolean. true if the last check succeeded, false otherwise.
uptime_percentage_24h	Uptime percentage in the past 24 hours.
uptime_percentage_7d	Uptime percentage in the past 7 days.
uptime_percentage_30d	Uptime percentage in the past 30 days.
last_check_time	ISO 8601 timestamp of the most recent check.
last_response_time_ms	Response time in milliseconds from the last successful check, or null if down.
current_status	String. "operational" if up, other values indicate issues.
error	String or null. Contains the error message if the last check failed.
monitor_enabled	Boolean. Whether monitoring is enabled for this domain.
has_ip	Boolean. Whether the domain has an IP address assigned.

Real-time status

The real-time status endpoint (GET /uptime/status/realtime) returns a list of all monitored domains with their current is_up status, fqdn, and last_check_time. This endpoint is optimized for quick polling to display live status without loading historical aggregates.

9. How to Interpret Results

Normal

• is_up: true and current_status: "operational" indicate the domain's target is reachable and responding.
• Uptime percentages near 100% indicate consistent availability. Minor dips below 100% can occur due to transient network issues or server reboots.
• last_response_time_ms is a small positive integer (typically under 200ms for local or well-connected hosts).

Unexpected or worth investigating

• is_up: false with an error message: The host is unreachable. Common errors include "Connection timeout", "Connection refused", or "Host unreachable". Verify the IP address is correct and the host is online.
• Uptime percentage below 95%: Indicates frequent or prolonged outages. Check network stability, host uptime, and whether the IP was updated correctly after a change.
• has_ip: false: The domain has no IP address assigned. Monitoring cannot perform connectivity checks. Assign an IP to resolve this.
• Sudden increase in average_response_time_ms: May indicate network congestion, increased server load, or routing issues. Compare against baseline response times.

Common interpretation mistakes

• Confusing uptime percentage with DNS propagation: Uptime monitoring checks whether the target IP is reachable, not whether DNS queries return the correct IP. A domain can have 100% uptime even if DNS changes are still propagating.
• Expecting monitoring to detect application failures: A host that responds to connectivity checks but has a failed web server or application will still show is_up: true. Uptime monitoring confirms network reachability only.
• Assuming domains_down: 0 means no issues: A domain with monitoring disabled does not contribute to the down count, even if its host is offline.

10. Common Issues and Explanations

"Monitoring limit reached for your plan" when enabling monitoring

You have enabled monitoring on the maximum number of domains for your plan. Free plan allows 5 monitored domains, Pro allows 50, and Elite allows 500. Disable monitoring on an existing domain or upgrade your plan to increase the limit.

Domain shows is_up: false but the host is online

Verify the IP address assigned to the domain matches the current IP of the host. If you recently updated the domain's IP, ensure the update was successful. Check firewall rules on the host to confirm ICMP or TCP connectivity checks are not blocked. Connectivity checks originate from CertaDNS's monitoring infrastructure; if your host restricts traffic to specific sources, the checks may fail.

Uptime percentage is 0% immediately after enabling monitoring

Uptime percentages are calculated from historical check data. If monitoring was just enabled, there is insufficient data to compute a meaningful percentage. Wait for at least one hour to see 24-hour data, and several days for 7-day and 30-day percentages to stabilize.

error: "Connection timeout" appears intermittently

Transient network issues or brief host downtime can cause occasional timeouts. If the error persists, verify the host is reachable from external networks, not just your local network. Check for network infrastructure issues or ISP routing problems.

API returns 404 when querying GET /uptime/domain/{domain_id}

The domain ID does not exist or does not belong to your account. Verify the domain ID is correct by listing your domains via GET /domains. Ensure you are authenticated with the correct API key or session token.

Monitoring icon is gray but API shows monitor_enabled: true

The dashboard UI may be cached. Refresh the page to sync the UI state with the backend. If the issue persists, check browser console for errors or try logging out and back in.

11. Limits and Constraints

Constraint	Free	Plus	Pro	Elite
Monitored domains	5	5	50	500
Data retention (hourly)	24 hours	24 hours	24 hours	24 hours
Data retention (daily)	30 days	30 days	30 days	30 days
API access	No	Yes	Yes	Yes

• Check frequency: System-managed, not user-configurable. Typical frequency is every 5 minutes, but this may vary based on system load.
• Data granularity: Hourly statistics in Redis for the past 24 hours, daily aggregates in PostgreSQL for 7-day and 30-day windows.
• Real-time status data is stored per-domain in Redis under uptime:domain:{domain_id}.
• Hourly stats are stored in Redis under uptime:stats:{domain_id}:{YYYYMMDDHH} and automatically expire after 24 hours.
• Daily aggregates in the uptime_daily table are retained for 30 days before archival or deletion.

12. Related Features

• Dynamic DNS Domains — The domains being monitored by the uptime system.
• DNS Analytics — Query volume and traffic analytics for your domains (separate from uptime monitoring).
• Dashboard Overview — Summary of account activity, including uptime monitoring status.
• Wildcard DNS — Wildcard domains can also be monitored for uptime if they have an IP assigned.
• Web Forwarding — Forwarded domains do not support uptime monitoring, as they redirect rather than resolve to an IP.

13. Updates and Behavior Changes

• Uptime monitoring limits for the Pro plan were increased from 25 to 50 monitored domains.
• The uptime_daily table was introduced to store daily aggregates, improving performance for 7-day and 30-day uptime queries.
• The GET /uptime/status/realtime endpoint was added to support lightweight real-time status polling without loading historical data.
• Redis key expiration was adjusted to automatically remove hourly stats older than 24 hours, reducing memory usage.