These are the basic things that I did to troubleshoot the issue (oracle.sysman.emSDK.emd.comm.CommException: rac02.localhost:cn=rac02).
1. Remove the Agent that was automatically discovered by OMS.
a. remove the components (listener, asm, database) of the Agent per node
b. remove the agent from the Grid. you need to shutdown MA first on the node
2. Edit the targets.xml file for each node under $MA_HOME/rac/sysman/emd.
a. put in the correct/fully-qualified host name (i.e. instead of rac01, put rac01.localhost)
b. put in the username and password for dbsnmp id as shown below.
<Property NAME=”UserName” VALUE=”dbsnmp”/>
<Property NAME=”password” VALUE=”<clear_text_password>” ENCRYPTED=”FALSE”/>
3. Secure the agent by executing ’emctl secure agent’ on each node.
4. Edit emd.properties ($MA_HOME/rac/sysman/config) to provide the fully-qualified host name for OMS location and Agent location (i.e. EMD_URL=https://rac03.localhost:3872/emd/main instead of EMD_URL=https://rac03:3872/emd/main)
5. Restart the MAs on each node and wait for OMS to discover them again. If all of the components were not discovered, add them using the Grid GUI interface.
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