According to the Google Webmaster informational site, there are
several reasons why a site that was once listed in Google would no
longer be listed.
Here is a summary of the possible reasons as listed by Google:
* For some reason, your site was not available to access when the
Google robot crawled the site, and was removed from the active index.
* The number of sites linking to your site has dropped, lowering the
ranking of your site and reducing the number of people who find your
site on Google.
* More sites with a higher ranking have been found by Google, lowering
the relevant ranking of your site.
* Google has multiple "copies" of its index, and it may take several
weeks to be listed in all of them. In the meantime, sometimes your
site may be returned on a Google search, and sometimes it may not.
* A temporary glitch on Google's end caused your site not to be
reindexed, dropping it from Google.
* Your site was manually removed by Google editors because it did not
conform to quality standards as determined by Google.
For more details, please see the Google Webmaster informational page
Google Webmaster Resources
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