Nice explanation in the piece from Bret Fausett, who publishes Lextext.com.
When a domain expires and changes hands, Mr. Fausett said, Google can now more easily find, scan and index the new site, so it does not mistakenly point searchers to a site with irrelevant content, or place advertisers on sites with content that does not match their products or services.
That alone could profoundly affect the domain name market, which has rebounded partly because of another Google service, AdSense. Through AdSense, Google pays publishers to display text ads related to a site’s content. Speculators often buy the expiring domains of even marginally popular Web sites and replace the site’s content. But because the practice diminishes the usefulness of Google’s search engine, the company has long sought ways to curb it.
I’m not quite sure about that explanation of Google becoming a registrar purely for identifying expiring and deleted domains. The deletion cycle is often 45 days or more and during that time, an expired domain can be reactivated with the same content and on the same IP. Now if the domain was flagged as expired (it would be dropped from the zonefile – the big list of domains and nameservers) and reactivated it would be possible to compare the data with the cached web data. A deleted domain when it is bought, typically has a new set of nameservers and a new website IP. To do it properly would require more than access to the list of expiring and pending deletion domain names. The historical nameserver and website IP data would be required.
Part of the work I do is in tracking domain name movements to produce reports on hoster domain counts for the approximate 700K hosters in com/net/org/biz/info/ie. The other part of my work is producing search engine lists of websites for individual countries. It would be far easier for Google to rely on the domain/nameserver data from the zonefiles and use this to generate new and deleted website listings. If I can do it on a desktop machine for the com/net/org/biz/info/ie zones, I don’t see why Google can’t do it too.
The one possibility that nobody seems to have considered is that Google is looking at the whole registrar thing from the point of view of operating a domain registry for an as yet undecided gTLD. Just imagine if Google was able to integrate gmail with for example something like .email or .mob.
imagine what happens if you have both the information of the (in)linkstructure of a particular domain AND the expiration date. Take all the domains with many high PageRank inlinks and…