static long
checkU32(String field, long val) {
	if (val < 0 || val > 0xFFFFFFFFL)
		throw new IllegalArgumentException("\"" + field + "\" " + val + 
						   " must be an unsigned 32 " +
						   "bit value");
	return val;
}
Returns the name for which additional data processing should be done
for this record.  This can be used both for building responses and
parsing responses.
@return The name to used for additional data processing, or null if this
record type does not require additional data processing.
src/main/java/core/org/xbill/DNS/Record.java