for (int i = 0; i < IPV4_PART_COUNT; i++) {
      int end = ipString.indexOf(IPV4_DELIMITER, start);
      if (end == -1) {
        end = ipString.length();
      }
      try {
        bytes[i] = parseOctet(ipString, start, end);
      } catch (NumberFormatException ex) {
        return null;
      }
      start = end + 1;
    }

    return bytes;
  }