With HA configured the hdfs shell (org.apache.hadoop.fs.FsShell) seems to issue a DNS query for the cluster Name. if fs.defaultFS is set to hdfs://mycluster, then the shell seems to issue a DNS query for mycluster.FQDN or mycluster.
since mycluster not a machine name DNS query always fails with
"DNS 85 Standard query response 0x2aeb No such name"
- Setup a HA cluster
- Log on to any node
- Run wireshark monitoring port 53 - "sudo tshark 'port 53'"
- Run "sudo -u hdfs hdfs dfs -ls /"
- You should be able to see DNS queries to mycluster.FQDN in wireshark