Matt Cutts once said in 2007:
We hear complaints about some kind of search (such as esoteric or long tail words), Google returns too much from the same domain, and we will improve the algorithm in the next few weeks to reduce its chance of appearing.
Then Google released a sitelinks to solve the problem, but this phenomenon has recently looked up and intensified the wind, such as your search for Apple itunes will find that Google gives a lot of search results from apple.com, although it also contains search results from apple.com, but a few, 31 of the top 50 search results are from apple.com!
Try to search Yahoo Mail again also, you can only see a lot of boring information from Yahoo International website, but do not see the news, blog, Evaluation and hands-on guide on yahoo email:
Then search Berkeley College, where 26 out of the top 50 results came from berkeley.edu.com, you had to look at other information about Berkeley by adding "-site:berkeley.edu.com" to the search keyword. But obviously this approach is troublesome and only a handful of people know how to use it.
In the search results show too much from the same domain name content is a bit of "lazy" idea, search engines should be able to provide information from a variety of channels, if I see all from the same domain name in the content, and I go directly to the official website search What is the difference?
Google is actually indexing more and more content, but they forget to make it "easy".
Via GOS