JBoss 4.2 on Windows Server 2003

How does JBoss-4.2 resolve DNS names - in creating InitialContext or in other uses?

I understand that one could use a property DNS_URL to specify a DNS to resolve these names by. But we have not set this property but the names are still resolved successfully! I'd appreciate any help in understanding the real mechanism.

Could it be using the hosts file to do this resolution? Anthing else?

Thanks