# File lib/dnsruby/message/header.rb, line 222
  def decode(msg)
    @id, flag, @qdcount, @ancount, @nscount, @arcount =
        msg.get_unpack('nnnnnn')
    @qr = ((flag >> 15) & 1) == 1
    @opcode = OpCode.new((flag >> 11) & 15)
    @aa = ((flag >> 10) & 1) == 1
    @tc = ((flag >> 9)  & 1) == 1
    @rd = ((flag >> 8)  & 1) == 1
    @ra = ((flag >> 7)  & 1) == 1
    @ad = ((flag >> 5)  & 1) == 1
    @cd = ((flag >> 4)  & 1) == 1
    @rcode = RCode.new(flag & 15)
  end