results: MutableList<InetAddress>,
    failures: MutableList<Exception>,
  ) {
    try {
      val addresses = readResponse(hostname, response)
      synchronized(results) {
        results.addAll(addresses)
      }
    } catch (e: Exception) {
      synchronized(failures) {
        failures.add(e)
      }
    }
  }

  @Throws(UnknownHostException::class)
  private fun throwBestFailure(