is 127.0.0.1 mapped to localhost in your machine, C:\Windows\System32\drivers\etc\hosts

hi Shaila,
Once you start Firefox in Cloudera VM, it opens a "Cloudera MAnager" link . Login to this link using "Cloudera/cloudera". Once logged in, you will be taken to "All services" page where all the services will be listed. Check the status of "HDFS1" in this page and if its down, select "Restart" from the drop down on this line. Once the service is started, try the commands on the terminal to validate.

Thanks

@Anish, 127.0.0.1 is already mapped to localhost in my machine.

@DeZyre Support, I tried to restart the HDFS1 but Namenode failed to re-start.
Below is the error-
2015-05-06 16:44:30,142 FATAL org.apache.hadoop.hdfs.server.namenode.NameNode: Exception in namenode join
java.io.IOException: Gap in transactions. Expected to be able to read up until at least txid 876 but unable to find any edit logs containing txid 876
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.checkForGaps(FSEditLog.java:1194)
at org.apache.hadoop.hdfs.server.namenode.FSEditLog.selectInputStreams(FSEditLog.java:1152)
at org.apache.hadoop.hdfs.server.namenode.FSImage.loadFSImage(FSImage.java:623)
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:274)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFSImage(FSNamesystem.java:639)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.loadFromDisk(FSNamesystem.java:476)
at org.apache.hadoop.hdfs.server.namenode.NameNode.loadNamesystem(NameNode.java:403)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:437)
at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:613)
at org.apache.hadoop.hdfs.server.namenode.NameNode.(NameNode.java:598)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1169)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1233)
2015-05-06 16:44:30,144 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 1
2015-05-06 16:44:30,150 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at localhost.localdomain/127.0.0.1
************************************************************/