public static synchronized void
refreshDefault() {

	try {
		defaultResolver = new ExtendedResolver();
	}
	catch (UnknownHostException e) {
		throw new RuntimeException("Failed to initialize resolver");
	}
	defaultSearchPath = ResolverConfig.getCurrentConfig().searchPath();
	defaultCaches = new HashMap();
	defaultNdots = ResolverConfig.getCurrentConfig().ndots();
}
The host exists, but has no records associated with the queried type.
src/main/java/core/org/xbill/DNS/Lookup.java