Update: 11/20/2016 For using Ambari-agent , must include this vital missing code when editing ambari server hostname in /etc/ambari-agent/conf/ambari-agent.ini. I couldn' get the host to talk to Ambari server until i put this (ip_addres=x.x.x.x) in. vi /etc/ambari-agent/conf/amabari-agent.ini [server] hostname=your.ambari_server.name ip_address=x.x.x.x <--------------this is most important to ensure the host can talk to ur ambari server url_port=8440 secured_url_port=8441 ... View more