Spark fails to register multiple workers to master - apache-spark

Question

I have been working on creating a Spark cluster using 1 master and 4 workers on Linux.
It works fine for one worker. When I try to add more than one worker, only the first worker gets registered to master while the rest fails with the below error,
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
18/08/06 14:17:39 INFO Worker: Started daemon with process name: 24104#barracuda5
18/08/06 14:17:39 INFO SignalUtils: Registered signal handler for TERM
18/08/06 14:17:39 INFO SignalUtils: Registered signal handler for HUP
18/08/06 14:17:39 INFO SignalUtils: Registered signal handler for INT
18/08/06 14:17:39 WARN NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
18/08/06 14:17:39 INFO SecurityManager: Changing view acls to: barracuda5
18/08/06 14:17:39 INFO SecurityManager: Changing modify acls to: barracuda5
18/08/06 14:17:39 INFO SecurityManager: Changing view acls groups to:
18/08/06 14:17:39 INFO SecurityManager: Changing modify acls groups to:
18/08/06 14:17:39 INFO SecurityManager: SecurityManager: authentication disabled; ui acls disabled; users with view permissions: Set(barracuda5); groups with view permissions: Set(); users with modify permissions: Set(barracuda5); groups with modify permissions: Set()
18/08/06 14:17:40 INFO Utils: Successfully started service 'sparkWorker' on port 46635.
18/08/06 14:17:40 INFO Worker: Starting Spark worker 10.0.6.6:46635 with 4 cores, 14.7 GB RAM
18/08/06 14:17:40 INFO Worker: Running Spark version 2.1.0
18/08/06 14:17:40 INFO Worker: Spark home: /usr/lib/spark/spark-2.1.0-bin-hadoop2.7
18/08/06 14:17:40 INFO Utils: Successfully started service 'WorkerUI' on port 8081.
18/08/06 14:17:40 INFO WorkerWebUI: Bound WorkerWebUI to 0.0.0.0, and started at http://10.0.6.6:8081
18/08/06 14:17:40 INFO Worker: Connecting to master Cudatest.533gwuzexxzehbkoeqpn4rgs4d.ux.internal.cloudapp.net:7077...
18/08/06 14:17:40 WARN Worker: Failed to connect to master Cudatest.533gwuzexxzehbkoeqpn4rgs4d.ux.internal.cloudapp.net:7077
org.apache.spark.SparkException: Exception thrown in awaitResult
at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:77)
at org.apache.spark.rpc.RpcTimeout$$anonfun$1.applyOrElse(RpcTimeout.scala:75)
at scala.runtime.AbstractPartialFunction.apply(AbstractPartialFunction.scala:36)
at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59)
at org.apache.spark.rpc.RpcTimeout$$anonfun$addMessageIfTimeout$1.applyOrElse(RpcTimeout.scala:59)
at scala.PartialFunction$OrElse.apply(PartialFunction.scala:167)
at org.apache.spark.rpc.RpcTimeout.awaitResult(RpcTimeout.scala:83)
at org.apache.spark.rpc.RpcEnv.setupEndpointRefByURI(RpcEnv.scala:100)
at org.apache.spark.rpc.RpcEnv.setupEndpointRef(RpcEnv.scala:108)
at org.apache.spark.deploy.worker.Worker$$anonfun$org$apache$spark$deploy$worker$Worker$$tryRegisterAllMasters$1$$anon$1.run(Worker.scala:218)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.io.IOException: Failed to connect to Cudatest.533gwuzexxzehbkoeqpn4rgs4d.ux.internal.cloudapp.net:7077
at org.apache.spark.network.client.TransportClientFactory.createClient(TransportClientFactory.java:228)
at org.apache.spark.network.client.TransportClientFactory.createClient(TransportClientFactory.java:179)
at org.apache.spark.rpc.netty.NettyRpcEnv.createClient(NettyRpcEnv.scala:197)
at org.apache.spark.rpc.netty.Outbox$$anon$1.call(Outbox.scala:191)
at org.apache.spark.rpc.netty.Outbox$$anon$1.call(Outbox.scala:187)
... 4 more
Caused by: java.nio.channels.UnresolvedAddressException
at sun.nio.ch.Net.checkAddress(Net.java:101)
at sun.nio.ch.SocketChannelImpl.connect(SocketChannelImpl.java:622)
at io.netty.channel.socket.nio.NioSocketChannel.doConnect(NioSocketChannel.java:242)
at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.connect(AbstractNioChannel.java:205)
at io.netty.channel.DefaultChannelPipeline$HeadContext.connect(DefaultChannelPipeline.java:1226)
at io.netty.channel.AbstractChannelHandlerContext.invokeConnect(AbstractChannelHandlerContext.java:550)
at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:535)
at io.netty.channel.ChannelOutboundHandlerAdapter.connect(ChannelOutboundHandlerAdapter.java:47)
at io.netty.channel.AbstractChannelHandlerContext.invokeConnect(AbstractChannelHandlerContext.java:550)
at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:535)
at io.netty.channel.ChannelDuplexHandler.connect(ChannelDuplexHandler.java:50)
at io.netty.channel.AbstractChannelHandlerContext.invokeConnect(AbstractChannelHandlerContext.java:550)
at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:535)
at io.netty.channel.AbstractChannelHandlerContext.connect(AbstractChannelHandlerContext.java:517)
at io.netty.channel.DefaultChannelPipeline.connect(DefaultChannelPipeline.java:970)
at io.netty.channel.AbstractChannel.connect(AbstractChannel.java:215)
at io.netty.bootstrap.Bootstrap$2.run(Bootstrap.java:166)
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:408)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:455)
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:140)
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:144)
... 1 more
Let me know if I have missed something here. Or if anyone knows what might be the solution to this.
Thanks