I would like to bring attention to the following issue happening with 4.0.5.GA Windows 2003 I have a test application which works fine on IPv4 set-up cluster with nodes bound to host IPv4 ip addresses. Same application deployed to identically set-up cluster on IPv6 dual stack ( -Djava.net.preferIPv4Stack=true). The application fails to access HA JMS on jnp://localhost:1100 - . Localhost is resolved as ::1. 127.0.0.1 is pingable but can not be a substitution to localhost on IPv6 dual stack - binding is denied. A work around in this case was to substitute localhost with actual machine's IP in the ear, which is not feasible with farm deployment This is the exception on new InitialContext(). Test application can be e-mailed upon request or uploaded. javax.naming.NamingException: Could not dereference object [Root exception is javax.naming.CommunicationException: Could not obtain connection to any of these urls: localhost:1100 and discovery failed with error: javax.naming.CommunicationException: Receive timed out [Root exception is java.net.SocketTimeoutException: Receive timed out] [Root exception is javax.naming.CommunicationException: Failed to connect to server localhost:1100 [Root exception is javax.naming.ServiceUnavailableException: Failed to connect to server localhost:1100 [Root exception is java.net.ConnectException: Connection refused: connect]]]] at org.jnp.interfaces.NamingContext.resolveLink(NamingContext.java:1067) at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:700) at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:716) at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:587) at javax.naming.InitialContext.lookup(InitialContext.java:351) Thank you in advance, Irena View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4152688#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...