Google recently released a Help document explaining how network and DNS errors and HTTP status codes affect the results of a website’s search. The document is currently in English only, but here are the basics.
If network errors occur, site crawling slows down. If the already indexed addresses become unavailable, they will be removed from the search results in a few days. DNS and network errors will badly affect the results of sites, reducing the number of issues.
HTTP status codes
The help is followed by a description of the codes and how GoogleBot reacts to them:
- 5XX and 429 – there is a temporary slowdown in page scanning;
- 4XX – pages are not indexed; if they were indexed earlier, they are removed from the list;
- 3XX – redirect code, during which the system will follow the linked links 10 times, trying to establish contact;
- 2XX – this value means that the system will consider the possibility of indexing the page.