I used a different website copier right after I got this message from HTTrack,
and it had no problem getting the pages.  No DNS error, no errors at all. 
Unfortunately, the Website Ripper Copier free version has a 500 files limit,
so I can't use it for the whole site.

But it shows that there isn't a problem with the DNS or the site I'm trying to
copy, because other software can do it.  But I try HTTrack right before
Website Ripper Copier and right after, and it gives me errors.