ICMP Checks
ICMP checks monitor host availability and network latency using ICMP Echo (ping) requests. They are the simplest way to verify that a host is reachable on the network.
When to Use ICMP Checks
Use ICMP checks when you need to monitor basic network reachability:
- Network devices - Routers, switches, firewalls, and load balancers
- Bare-metal servers - Hosts where no HTTP service is running
- Infrastructure endpoints - DNS servers, gateways, and network appliances
- IP-based services - Any host identified by IP address or hostname
- Latency tracking - Measure round-trip time to any host on the internet
Configuration
Host
Enter the hostname or public IP address of the target to monitor. Both IPv4 addresses and domain names are supported.
Note: Private IP addresses (127.0.0.1, 10.x, 172.16-31.x, 192.168.x) and reserved addresses are not allowed.
Check Frequency
Set how often the ICMP check runs:
- Free tier - Minimum 5-minute intervals
- Nano tier - Minimum 1-minute intervals
Response Time Limit
Set the maximum acceptable round-trip time in milliseconds. If the ping response exceeds this threshold, the check can be flagged for slow performance.
How It Works
- An ICMP Echo Request packet is sent to the specified host
- The system waits for an ICMP Echo Reply from the target
- If a reply is received, the check is marked as UP and the round-trip time (RTT) is recorded
- If no reply is received within the timeout period, the check is marked as DOWN
- On first failure, an automatic 30-second re-check is performed to prevent false alerts
- After 4 consecutive failures within 5 minutes, an alert is triggered
Performance Metrics
ICMP checks record the following metrics:
| Metric | Description |
|---|---|
| Round-Trip Time (RTT) | Time in milliseconds for the packet to reach the host and return |
| TTL (Time To Live) | Number of network hops remaining, useful for routing diagnostics |
| Target IP | Resolved IP address of the hostname |
| IP Family | Whether the connection used IPv4 or IPv6 |
Additionally, each check enriches results with geographic metadata including country, region, city, ASN, ISP, and organization information for the target host.
Best Practices
- Use ICMP for infrastructure, HTTP for applications - ICMP checks verify network reachability but cannot validate application health. Use website checks or API checks for application-level monitoring.
- Combine with other check types - Monitor the same host with both ICMP and HTTP/TCP checks for comprehensive coverage.
- Set realistic response time limits - Typical RTT varies by distance. Local hosts respond in under 10ms, while intercontinental targets may take 100-300ms.
- Monitor network devices directly - Routers and switches often don’t run HTTP services, making ICMP the ideal check type.
Limitations
- ICMP checks only verify network reachability, not application-level health
- Some hosts and firewalls block ICMP traffic, which would cause false-negative results
- Response validation is not available for ICMP checks
- SSL monitoring is not applicable to ICMP checks
- Only one ICMP packet is sent per check (no multi-packet loss analysis)