I know that a rating of "domain authority" is a bit subjective and different engines can have different parameters.
But let's say I have a newly created website for my aunt. It is new and has NO authority whatsoever.
On a page like moz.com, it has the lame authority of 0.
Is it bad to put a backlink on my aunt's webpage pointing at my website: "Website designed by my beloved nephew example.com"? It could be just neutral, not good but not bad.
But then it comes the second question, Imagine some backlinks from spammy websites can be attacking my website. Is there any way to find harmful websites with some kind of negative domain authority?
Related questions: Is page authority or domain authority more important for backlinks?
How to identify spammy domains giving backlinks to my site (to submit in disavow links in WMT) (but links on this answer are no longer active)