Let me begin by saying..... this is a bit above my pay grade.  :)

I did  copy a header of a message I sent to my brother, pasted it in the header analyzer, and ran it.

This is what I saw:

 red circle with "x" in it, followed by DMARK Compliant   (No DNS found)

red circle with "x" in it, followed by SPF Alignment

green circle with a checkmark in it, followed by SPF Authenticated

red circle with "x" in it, followed by DKIM Alignment

red circle with "x" in it, followed by DKIM Authenticated

So, explain to me..... when it says "No DNS found", what exactly does that mean?

I will conclude by saying..... This is all Greek to me.   :)