This post is the part of SEO Tips that I have been writing recently on my blog and you can find them here and here. If somehow Google is not Indexing your Website pages100% in its Index or you have noticed sudden decrease in the Indexed pages then you are not alone. Recently I found on SEOmoz that this is a very common problem nowadays for websites having huge content. So apparently as I suspected and mentioned by SEOmoz in above post, Google has Indexation Cap for every website.
Which means they will not Index the pages beyond a certain limit for a Website. If you have a small Website with few number of pages then you would most probably not be effected and most of your Website pages would be Indexed by Google. However If you have huge Website with hundreds or thousands of pages then you are most likely to see this effect.
And I experienced the same problem with one of my blogs having hundreds of posts. And When I actually found that a good number of posts are not Indexed by Google it led me to investigate this matter further. I am not an SEO expert However quick Search and review of other Websites in my niche that relatively have more pages Indexed in Google revealed they had good number of backlinks pointing to them. So if you really want to increase the Indexation cap limit then you must work on getting ‘quality backlinks’ and you can actually learn here how to get backlinks.
If someone copies content from else where as it is in a regular fashion, Google can detect it and would not index that site properly.