code: public synchronized String
  toMasterFile() {
  	Iterator zentries = data.entrySet().iterator();
  	StringBuffer sb = new StringBuffer();
  	nodeToString(sb, originNode);
  	while (zentries.hasNext()) {
  		Map.Entry entry = (Map.Entry) zentries.next();
  		if (!origin.equals(entry.getKey()))
  			nodeToString(sb, entry.getValue());
  	}
  	return sb.toString();
  }
docs: Returns the contents of the Zone in master file format.