Host Availability (ICMP/TCP) Monitoring
Host Availability (ICMP/TCP) Monitoring
Continuously test the reachability and network performance of any host using ICMP or TCP. Cloudmon measures availability, latency, jitter, and packet loss at every polling interval and maps the full network path with hop-by-hop trace path analysis.
Overview
Host Availability monitoring in Cloudmon uses active probing to verify that a host is reachable from a specific probe location and to measure the quality of the network path to that host. At every polling interval, Cloudmon sends ICMP echo requests or establishes a TCP connection to the target host and records the outcome. The result is a continuous availability and performance record that makes it easy to detect outages, packet loss events, and latency spikes as they happen.
Hosts are identified by IP address or FQDN. Any device that can be reached over a network can be monitored with Host Availability, making it the right tool for devices that do not support SNMP and do not have a Cloudmon agent installed, such as printers, IP cameras, unmanaged network devices, branch office routers, and on-premise servers outside your core SNMP estate.
Hosts can be added manually or discovered automatically using Network Discovery. Refer to Network Discovery for details on scanning IP ranges and adding discovered hosts to monitoring in bulk.
Configuration
To add a host manually, navigate to Synthetic → Network → Host Availability and click the + button. Fill in the fields as follows:
| Field | Description |
| Probe | The Cloudmon probe that will send test traffic to the host. Choose a probe in the same network segment as the target host for accurate results, or a remote probe to test reachability from a specific location. |
| Name | A descriptive label for this host as it will appear in the dashboard, such as "Branch Office Router" or "Production DB Server". |
| Hostname or IP | The IP address or fully qualified domain name (FQDN) of the host to monitor. |
| Monitoring Profile | The polling and reporting interval profile for this host. Profiles are configured under Settings → Configurations → Monitoring Profile → Network Nodes/Services. |
| Alarm Rule | Select an alarm rule to apply to this host from the dropdown of existing alarm rules configured under Configurations → Alarm Rules → Network Nodes/Services. |
| Protocol | Choose ICMP to test reachability with ping, or TCP to test reachability by connecting to a specific port. Use ICMP for general host availability checks. Use TCP for hosts where ICMP is blocked by a firewall. |
| Tags | Optional labels for filtering and grouping hosts in reports and dashboards. |
Click Save. Cloudmon begins polling the host at the configured interval immediately.
What Cloudmon Monitors
For each monitored host, Cloudmon tracks availability as a percentage of polling intervals in which the host responded, downtime duration when the host was unreachable, response time in milliseconds, latency jitter (variation in response time between intervals), and packet loss percentage. These metrics give a comprehensive view of both whether a host is up and how well the network path to it is performing.
Consistent packet loss to a branch office router, for example, indicates an unreliable WAN link even if the router itself stays online. Rising jitter on a VoIP gateway signals network instability that will cause call quality issues before users start complaining.
Trace Path
Trace Path provides a hop-by-hop analysis of the network route taken to reach a monitored host, helping diagnose connectivity issues and identify bottlenecks at specific network hops. To enable it, select a monitored host, navigate to Settings → Monitoring, and toggle Trace Path on. Set the desired trace path polling interval and click Save. Cloudmon will periodically trace the route to the host and display the full hop list with per-hop latency.
Alarms
Each alarm is built around a simple IF/THEN model, where you select a metric, set a threshold, and define what happens when it is breached. Learn more.
Troubleshooting
| Issue | What to check |
| Host shows as down but device is physically online | Verify that ICMP (ping) is not blocked by a firewall or ACL between the probe and the target host. If ICMP is blocked, switch the protocol to TCP in the host settings and specify a port that the device is known to have open. |
| Response time is consistently high for a specific host | Enable Trace Path on the host to identify which hop in the network route is introducing latency. Navigate to the host settings, toggle Trace Path on, and review the hop-by-hop latency in the next polling cycle to isolate the problem segment. |
| Host was added but never appears as Up | Confirm the probe selected during setup is online and in the same network segment as the target host. A probe in a different site cannot reach a host behind a firewall that blocks ICMP or TCP from that probe address. |
| Intermittent packet loss showing on a stable host | Check the physical network path for duplex mismatches, faulty cables, or oversubscribed uplinks. Use Trace Path to identify if the loss is occurring at the host itself or at an intermediate hop. Packet loss at a specific router hop indicates a congested or faulty link, not a host issue. |
| Alarms not firing when the host goes down | Verify an alarm rule is assigned to the host in its settings. Check that the rule has an availability trigger configured and that the notification recipients or third-party services are correctly set up in the alarm rule. |
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