Sat Dec 29 07:03:52 PST 2018

186
spikes in search volumes or news agencies writing a bunch of content about a
topic Google might be more likely to mix in fresher results.

Supplemental Results Index
When the supplemental index was first launched Google labeled the supplemental
results. SEOs came up with hacks for figuring out how many supplemental results
different websites had, and after they got popular Google disabled them and
removed the supplemental results label.
Google has an auxiliary index where it stores some documents it may not trust
enough to include in its regular index. Supplemental search results are used to
provide search results when not enough regular search results are available. Why
do sites get put in the supplemental results?
? Too much content for the amount of PageRank the site has. If a PR2
site has 100,000 pages Google isn? going to index most of them.
? Newness. If a site is new and does not have many inbound links, some
of its pages may end up in the supplemental results until the site builds
up its popularity and ages a bit. This is typical for some new URLs
that have not been crawled yet.
? Duplicate content. For example, giving a search engine multiple URLs
with the same content or a directory full of empty categories with near
similar content on every page
? Too many variables in the URL
? Host was down when Google tried to crawl
? Too many low-quality outbound links
? Too many low-quality inbound links
? Any combination of the above
Since pages in the supplemental results are not trusted as much as pages in the
regular index, it is likely that Google rarely crawls and places low or no weight on
links from many of the pages in the supplemental results.
Date Based Filters, Cache Date & Site Indexing Growth
Many analytics programs show what pages are crawled frequently by search
engines. If they crawl some parts of your site frequently it is safe to say they trust
that part of your site significantly because they keep spending bandwidth to visit it
frequently.
Google?s advanced search page allows you to search for pages that are recently
indexed. These search filters can be used to
? Find how well your site is getting indexed