I have made the changes, Now, it doesn't show unknown host, It helped me figure out that, still I have same proble, just that, now my error is like, at line 163 2018-08-17 13:49:18,455 FATAL [localhost:16000.activeMasterManager] master.HMaster: Failed to become active master java.net.ConnectException: Call From "saichanda-OptiPlex-9020/127.0.0.1" to master:50000 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused at line 213 2018-08-17 13:49:18,456 FATAL [localhost:16000.activeMasterManager] master.HMaster: Unhandled exception. Starting shutdown. java.net.ConnectException: Call From "saichanda-OptiPlex-9020/127.0.0.1" to master:50000 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused the updated log file has been attached here . Another mention.. I don't have any directory called <sysconfig> in my /etc file, do I need create directory named sysconfig and then write into file 'network' ? or Is there anything that I'm missing out? Also, If you can help me figure out what is FQDN(<fully.qualified.domain.name>)... Thank you sir. ... View more