我在centos-6.5_x64 上安装hadoop-2.7.2 集群，无法格式化zkfc（bin/hdfs zkfc -formatZK），报找不到主机的错误，如下：
INFO zookeeper.ZooKeeper: Initiating client connection, connectString=node01:2181;node02:2181;node03:2181 sessionTimeout=5000 watcher=org.apache.hadoop.ha.ActiveStandbyElector$WatcherWithClientRef@5193e02f
16/08/15 10:07:12 FATAL tools.DFSZKFailoverController: Got a fatal error, exiting now
java.net.UnknownHostException: node01:2181;node02:2181;node03
at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method)
at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:901)
at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1295)
at java.net.InetAddress.getAllByName0(InetAddress.java:1248)
at java.net.InetAddress.getAllByName(InetAddress.java:1164)
at java.net.InetAddress.getAllByName(InetAddress.java:1098)
at org.apache.zookeeper.client.StaticHostProvider.<init>(StaticHostProvider.java:61)
at org.apache.zookeeper.ZooKeeper.<init>(ZooKeeper.java:445)
at org.apache.zookeeper.ZooKeeper.<init>(ZooKeeper.java:380)
at org.apache.hadoop.ha.ActiveStandbyElector.getNewZooKeeper(ActiveStandbyElector.java:631)
at org.apache.hadoop.ha.ActiveStandbyElector.createConnection(ActiveStandbyElector.java:775)
at org.apache.hadoop.ha.ActiveStandbyElector.<init>(ActiveStandbyElector.java:229)
at org.apache.hadoop.ha.ZKFailoverController.initZK(ZKFailoverController.java:350)
at org.apache.hadoop.ha.ZKFailoverController.doRun(ZKFailoverController.java:191)
at org.apache.hadoop.ha.ZKFailoverController.access$000(ZKFailoverController.java:61)
at org.apache.hadoop.ha.ZKFailoverController$1.run(ZKFailoverController.java:172)
at org.apache.hadoop.ha.ZKFailoverController$1.run(ZKFailoverController.java:168)
at org.apache.hadoop.security.SecurityUtil.doAsLoginUserOrFatal(SecurityUtil.java:415)
at org.apache.hadoop.ha.ZKFailoverController.run(ZKFailoverController.java:168)
at org.apache.hadoop.hdfs.tools.DFSZKFailoverController.main(DFSZKFailoverController.java:181)
请问一下，可能是什么原因导致了这个错误（zookeeper运行正常）？