One, the server is stable
1.1, the IDC network stability can ensure that the search engine spider access to my host, this can be in Baidu Webmaster tools
1.1.1, grasping frequency
The above two pictures we can see www.111cn.net crawl frequency 1.5W, time in 1 seconds is normal
1.1.2, grasping diagnosis
Check whether the crawl is normal, if the normal can enter the "crawl diagnostics" to see if it is not your IP address, if not correct, crawl failure do not need me to say update IP can.
1.1.3, crawl anomaly
This is a place to see connection errors and timeout or crawl times and DNS errors.
1.1.4, Index Quantity
This site contains a relationship with the above, a few days above the problem will certainly be included in the reduction.
1.2, the server load is too large, resulting in insufficient bandwidth or resources to cause a large number of 500 program errors
Two, whether the website was hacked
2.1, whether Baidu Webmaster reported a security bug
2.2. Whether the website content is embedded in the Trojan or gambling website
We're going to have to do this by myself, scanning the software.