Wirred query from none existing hosts in /var/log/zabbix/zabbix_server.log

[Heinrich]

Dear community,
monitoring the zabbix_server.log, I found a lot of messages comming in every second that look like this:

"1297:20580516:082334.269 cannot send list of active checks to "10.150.1.15": host [xxxxxxxx] not found" with100x different IPs

what´s wondering me, I do not use any active checks (as far as I know) and when i try to search for the ip in Zabbix, nothing appears.
where could this message come from?
"...cannot send list of active checks to...." shouldn´t this only be the case, when using active agents and the server trys to send its list of requirements to the agent?
thanks in advance for any hint.
Yours Heinrich

[cyber]

This line says, that your server cannot find the host in its hosts list, which comes to ask for config data. So it is ok, that you do not find that host in Zabbix, it is not registered there and no config is prepared for it. But as it seems there is some host(s) in your network, which tries to ask for config, so you should maybe track the other way and try to find out what host that is and why does it do this...

[Heinrich]

Thank you cyber. I am pretty sure you´re right. I guess on some of these "not yet hosted machines" is the agent installed and the server takes notice of em. Thanks for your help!
Yours Heinrich