hello I downloaded HDP AMI on AWS and started working on practice problem.
My command was
hadoop fs -mkdir fligtdelays
However even simple command to create dir gives error indicating node manager cannot be accessed from
namenode:8020 failed to connect
Try the solution here - sounds like your services are not running:https://community.hortonworks.com/questions/10884/connection-refused-aws-hdpcd-practice-exam-getting.html