I maintain some English websites in the company, mainly doing some daily SEO work, such as adding links, making some keywords, etc. However, since March 2009, the website has often been filled with hidden links. This is a typical hacker intrusion. A backdoor may have been added to the website system. Since then, hidden links have often been added to the homepage. Although it has been covered, a day or two later, hidden links have been added to the homepage again. But for this matter, I just perfunctoryly checked the log file and couldn't find any clues, so I didn't take it seriously. I thought it was just adding a few links and it was no big deal.
On June 19th, I checked the website in the morning and saw that the number of website visits had dropped significantly. I felt strange. I saw that the visitors were all coming from Yahoo! and Bing, but not from Google. I looked at the Google administrator tools to see. As early as the 17th, Google sent me an email to inform me that the website had been deleted because of adding hidden text. I was shocked, so I downloaded the entire website, found the hacker backdoor, deleted it, modified the page, and resubmitted for review. Two days later, on the morning of the 21st, I found that the website had been re-indexed, and the ranking position had basically remained unchanged.
There are several issues that are worth noting. On the 17th, Google sent an email to notify the deletion of the index, but there was still traffic from Google on that day. By the 19th, there was no traffic from Google at all, resulting in a change in the number of visits. It is very obvious, that is to say, even if the Google search quality team sent an email saying that the index has been deleted, in fact the index has not been completely deleted, there is still traffic coming from Google, and two days later, Google re-included the website, and the ranking is basically not there. The number of indexed pages has not changed much from before, but what is particularly noteworthy is that I found that the Google snapshot of the homepage is from June 18th. This discovery is indeed quite shocking, that is to say, After deleting the index, Google spider still crawls the page.
After deleting the index on the 19th, the entire website was not searchable on Google. Later, it was re-indexed. I saw that most of the page snapshots were from before the 17th. If I analyze it carefully, I would say that the index is really Has it been completely erased from the index database by Google? I'm afraid not necessarily, otherwise the snapshot date will not be the date before deletion, but the date of re-crawling after review.
Here, I boldly make a conjecture. No one knows the algorithm of Google search engine, but there are some traces that can be guessed. I wonder: Does Google adopt such a strategy and have a dedicated server to store the punished or deleted files? The website, just like Google Sandbox, even the processing method of deleted index web pages is another manifestation of Google Sandbox. When a website is deleted from the index, all the indexes are moved to such a server. In the normal ranking index These websites will no longer exist in , but spiders will still visit these blocked websites, which can be seen through the snapshot date. Otherwise, it can also be seen through the server's log file. Once the website is re-examined and passed , it will take a very short time to move from such a server to the normal index. This is why once the review is passed, the number of included pages will return from 0 to the previous level. If it is re-included, there should not be such a fast inclusion speed. .
I am just raising some issues I have discovered. I hope friends can put forward their own opinions and communicate with me.