writeShort(0) // answerCount
      writeShort(0) // authorityResourceCount
      writeShort(0) // additional

      val nameBuf = Buffer()
      val labels = host.split('.').dropLastWhile { it.isEmpty() }
      for (label in labels) {
        val utf8ByteCount = label.utf8Size()
        require(utf8ByteCount == label.length.toLong()) { "non-ascii hostname: $host" }
        nameBuf.writeByte(utf8ByteCount.toInt())