One thing I missed in August's post about the Google Dance 2005 lessons-learned in Google engineers on Link value, VIPS, Flash, Duplicate Content and crawler budget was that


* I got confirmed by Google engineers that the "trust" for a domain is instantly reset if the domain registration info changes, as new ownership means new control over the content.

* the same applies to expired domains, as expired domain buyers typically do that to gain old traffic, old rankings, old link popularity etc.

Furthermore it was said, that new IP adresses lead to a re-evaluation (i.e. of links) for the site, but typically no remove of "trust rank"-points…

So yes, Google does look at DNS changes – historically – and that means by changing the owner via DNS you actually hurt the sites top ranking.