hadoop unable to launch (NoRouteToHosterror)

[#1]

I've been trying to launch Hadoop by typing any command, for example, entering " Hadoop fs -ls" in the terminal and I get this error 

 WARN ipc.Client: Failed to connect to server: quickstart.cloudera/XXX.XXX.XX.128:8020: try once and fail.
java.net.NoRouteToHostException: No route to host
	at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
	at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739)
	at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
	at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
	at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:494)
	at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:648)
	at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:744)
	at org.apache.hadoop.ipc.Client$Connection.access$3000(Client.java:396)
	at org.apache.hadoop.ipc.Client.getConnection(Client.java:1557)
	at org.apache.hadoop.ipc.Client.call(Client.java:1480)
	at org.apache.hadoop.ipc.Client.call(Client.java:1441)
	at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:230)
	at com.sun.proxy.$Proxy16.getFileInfo(Unknown Source)
	at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.getFileInfo(ClientNamenodeProtocolTranslatorPB.java:786)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:260)
	at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:104)
	at com.sun.proxy.$Proxy17.getFileInfo(Unknown Source)
	at org.apache.hadoop.hdfs.DFSClient.getFileInfo(DFSClient.java:2131)
	at org.apache.hadoop.hdfs.DistributedFileSystem$20.doCall(DistributedFileSystem.java:1265)
	at org.apache.hadoop.hdfs.DistributedFileSystem$20.doCall(DistributedFileSystem.java:1261)
	at org.apache.hadoop.fs.FileSystemLinkResolver.resolve(FileSystemLinkResolver.java:81)
	at org.apache.hadoop.hdfs.DistributedFileSystem.getFileStatus(DistributedFileSystem.java:1261)
	at org.apache.hadoop.fs.Globber.getFileStatus(Globber.java:64)
	at org.apache.hadoop.fs.Globber.doGlob(Globber.java:272)
	at org.apache.hadoop.fs.Globber.glob(Globber.java:151)
	at org.apache.hadoop.fs.FileSystem.globStatus(FileSystem.java:1715)
	at org.apache.hadoop.fs.shell.PathData.expandAsGlob(PathData.java:326)
	at org.apache.hadoop.fs.shell.Command.expandArgument(Command.java:235)
	at org.apache.hadoop.fs.shell.Command.expandArguments(Command.java:218)
	at org.apache.hadoop.fs.shell.FsCommand.processRawArguments(FsCommand.java:102)
	at org.apache.hadoop.fs.shell.Command.run(Command.java:165)
	at org.apache.hadoop.fs.FsShell.run(FsShell.java:315)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:84)
	at org.apache.hadoop.fs.FsShell.main(FsShell.java:372)
ls: No Route to Host from  quickstart.cloudera/XXX.XXX.XX.128 to quickstart.cloudera:8020 failed on socket timeout exception: java.net.NoRouteToHostException: No route to host; For more details see:  http://wiki.apache.org/hadoop/NoRouteToHost

Notice Hadoop was running perfectly after my IP suddenly changed to XXX.XXX.XX.129. this error accrued. I don't know how to make/configure Hadoop launch on the same IP address 

Thank you

[#2]

Do you have the address quickstart.cloudera in /etc/hosts? If this is set incorrectly then trying to access the cluster using the hostname will always attempt to use the old address. Update the address in the hosts file and try again, see if that helps.

Regards,

Jim

[#3]

Surprisingly, I closed the vm and opened it again. then It launch fine.
I REALLY REALLY THANK YOU

[#4]

How to update host can u please give me a steps to do

[#5]

Edit the file /etc/hosts. It maps the hostname to the IP address. In most cases the quickstart VM gets this right, if you experience an issue restarting usually fixes it.

Regards,

Jim