after lack of my erlang understanding I decided to dig into tungd/elixir-dns code out of curiosity to see how it was handling things and it is doing what @evadne suggested and has some nice wrapper around erlang code which i ended up using. elixir-dns/record.ex at master · tungd/elixir-dns · GitHub

Big thanks to the elixir community for being supportive and having a solution to almost everything

Thanks @evadne passed the 1st hurdle , will upate the thread with progress for others if they ever need this info. might ping here if I hit a roadblock

post "/" do
    {:ok, body, conn} = Plug.Conn.read_body(conn)

    IO.inspect(body, label: "body")
    :inet_dns.decode(body) |> IO.inspect(label: "inet_dns.decode")
    conn
    |> put_resp_content_type("application/dns-message")
    |> send_resp(
      200,
      Jason.encode!(%{
        msg: "I don't have a heart but I am alive!"
      })
    )
  end

body: <<171, 205, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 3, 119, 119, 119, 7, 101, 120, 97, 
  109, 112, 108, 101, 3, 99, 111, 109, 0, 0, 1, 0, 1>>
inet_dns.decode: {:ok,
 {:dns_rec,
  {:dns_header, 43981, false, :query, false, false, true, false, false, 0},
  [{:dns_query, 'www.example.com', :a, :in}], [], [], []}}

Just for information, my DNS server written in Elixir uses (currently) the elixir-dns library. Because it does not seem actually maintained, I had to fork. My code may give you ideas.