Werk #19538: Host check: fall back to the Check_MK service status for push agents when smart ping is not possible
| Component | The Checkmk Micro Core | ||||
| Title | Host check: fall back to the Check_MK service status for push agents when smart ping is not possible | ||||
| Date | Apr 30, 2026 | ||||
| Level | Trivial Change | ||||
| Class | Bug Fix | ||||
| Compatibility | Incompatible - Manual interaction might be required | ||||
| Checkmk versions & editions |
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For hosts monitored by the Checkmk Micro Core, the default host check is smart ping. When smart ping is not possible on a push agent host — because the host has no resolvable IP address — Checkmk previously fell back to a regular ICMP ping, which would not succeed either.
The host check now derives the host state from the built-in Check_MK service for push agents in this situation — equivalent to selecting Use the status of the Check_MK Service in the Host check command ruleset.
The change is strictly scoped to push-agent hosts. Pull agents, hosts with a resolvable IP address, and hosts configured via Hosts with dynamic DNS lookup keep their previous behavior.
How to restore the previous behavior for a push agent
Configure a rule in Setup → Hosts → Host monitoring rules → Host check command for the affected hosts and pick PING (ICMP echo request) (or any other explicit choice that is not Smart ping). Any explicit choice other than Smart ping is honored as configured.
If Smart ping is explicitly selected on a push agent without a resolvable IP, the fallback still applies — smart ping cannot succeed in that situation — and a warning is emitted during configuration to make the override visible.
Note: relay-monitored hosts always derive the host state from the Check_MK service; explicit PING (ICMP echo request) or Smart ping rules are overridden with a warning, and no rule in the Host check command ruleset can restore ping behavior on such hosts.