what does "But the agents of servers is OK" mean? the service is running on the target? the appserver can talk to it ?
unknown host means the appserver can't resolve the target name that's registered in bsa.
so i would look at the job run log and look for an entry like 'running work item thread on appserver xxx for target yyy' where yyy is the 'unknown host'. then from appserver xxx rdp or ssh into it and run a 'ping yyy' - does it resolve ? does it resolve for all nameservers the appserver is set to use ? if you are using a socks proxy and the 'resolve on proxy' option is set in bsa, then check resolution on the proxy instead.
Yes. The agent of servers continuous running. I access the server on Bladelogic normally.
Ping resolves too.
How to check the socks proxy config?
Socks config is in infra mgr under socks proxies and network routing.
How many appservers do you have ? you checked ping from all of them ?
Ok, so start looking in the appserver logs for when this error happens in the job. look at the job run log, see what appserver was running the work item thread for the target and what time the error happened and find that in the appserver log. maybe there will be something useful.
How many dns servers are setup on the appservers ? what os are the appservers ?