By default, the Java instance running the runtime caches DNS resolution values.
So, in case of DNS address resolution update, it may be necessary to restart the Runtime to refresh its cache.
Alternatively, the Java property "sun.net.inetaddr.ttl" may be used in order to set a custom caching time, or even to disable caching.
To use this property with your runtime, you can update the initvariables file, adding (for example) "-Dsun.net.inetaddr.ttl=0" to the XDI_RUNTIME_VM_PROPERTIES variable content.
Example (Unix case):
XDI_RUNTIME_VM_PROPERTIES="-Djava.net.preferIPv4Stack=true -Dsun.net.inetaddr.ttl=0"
The runtime will have to be restarted to take this new parameter into account.
(sources: https://docs.oracle.com/javase/7/docs/technotes/guides/net/properties.html)