Agent is unable to communicate with the OMS

Sometimes the following fake alert wakes up the oncall DBA and clears itself after a couple of minutes due to the busy network.

Target Name=<host>:3872
Message=Agent is unable to communicate with the OMS. (REASON = Agent is Unreachable (REASON : Agent to OMS Communication is brokenError in request response).
Severity=Unreachable Start

Find target_guid for this target agent.
select target_guid from sysman.mgmt_targets where target_name='<host>:3872';

Increase max_inactive_time from the default value 120 sec to 240 sec.
SQL> update sysman.mgmt_emd_ping
  2  set  MAX_INACTIVE_TIME=240
  3  where target_guid='<target_guid>';