Nagios stopped to check host


Hi all,

I have had a nagios monitoring system running for 2 weeks and now the system stopped to check one of the hosts. It checks the services but not the host. Any idea about what logs to look for the problem or anyink that cal help?


Hi Marc,

my Name is Marc too… Nice to meet you and so on…

Ahm what Do you mean with “the System stopped to check a host”?
Can it be, that the Host is masked as Down but the Check for the Service is successful?

If this is what you mean, the Problem is the following:
To Check if the Host is alive, Nagios use the directive, named check_alive or so.
Nagios will try to PING theese Host. If the Systemadministrator of the Host, you want to PING, don’t allows this action, Nagios masked the Host as DOWN becuae Nagios gets a negative Response…

Many Greetings



from the nagios host i’m able to ping the remote host, but nagios doesn’t mark the host us ‘up’.

I’ve deleted the host from the config files and then I’ve configured it again and now I have the following message.

“This host has not yet been checked, so status information is not available.”

How can i check if there is some cache or how can i check the plugin output?




This seems to be one of the most common problems for new user of Nagios. Most all of the time this problem is due to an incorrect command definition for the host check command you specified in the host definition.

Make sure that the host check command in your host definition is configured correctly. The host check command is not a service - it is part of the host definition. Also, the host check command is not executed at regular intervals like a service is. Rather, it is executed only when Nagios finds it necessary to check the status of the host.

Important! Just because you have a service that is monitoring ping statistics for a host does not mean that the actual host status is being checked. The status of a host is only checked when a service check results in a non-OK state or if the host was previously down and a service check results in an OK state.

Some symptoms of incorrect host check commands include:

[list]Hosts incorrectly being listed as DOWN [/list:u]
[list]Hosts incorrectly being listed as UNREACHABLE [/list:u]
[list]Alternating alerts/notifications about host problems and recoveries[/list:u]

Marc, show me your host_definition Directive…

Your Namesake