I encountered this problem before. If t you can ping the machine using its name, but cannot ping it using its IP address.
then what you have to do is add the mapping into /etc/hosts -----Original Message----- From: bharathvissapragada1...@gmail.com [mailto:bharathvissapragada1...@gmail.com] On Behalf Of bharath vissapragada Sent: 2009年6月23日 6:42 To: core-user@hadoop.apache.org Subject: UnknownHostException when i try to execute the command bin/start-dfs.sh , i get the following error . I have checked the hadoop-site.xml file on all the nodes , and they are fine .. can some-one help me out! 10.2.24.21: Exception in thread "main" java.net.UnknownHostException: unknown host: 10.2.24.21. 10.2.24.21: at org.apache.hadoop.ipc.Client$Connection.<init>(Client.java:195) 10.2.24.21: at org.apache.hadoop.ipc.Client.getConnection(Client.java:779) 10.2.24.21: at org.apache.hadoop.ipc.Client.call(Client.java:704) 10.2.24.21: at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:216) 10.2.24.21: at org.apache.hadoop.dfs.$Proxy4.getProtocolVersion(Unknown Source) 10.2.24.21: at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:319) 10.2.24.21: at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:306) 10.2.24.21: at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:343) 10.2.24.21: at org.apache.hadoop.ipc.RPC.waitForProxy(RPC.java:288)
