Receiving errors on your site can discredit the reputation of your site; but Google invented a more detailed Site Error information in Webmaster Tools – the information is handy when looking for the source of your site errors.
How is that possible?
You might be wondering how Google initiated this site error information; well, here is to how: if you site experiences server connectivity problems, it means that your server is misconfigured it may also mean that the server is completely unavailable. Given that each site error (DNS, Server connectivity ad robots.txt Fetch) is compromised of several unique issues, Google broke down each type into more exact errors to offer you with an improved analysis of your site’s health.
As such, site errors will display on each of your website’s wide crawl errors from the past 90 days. Apart from that, the site will display the failure rates for any category-specific errors that have been disturbing your site.
What to do when you aren’t sure what a particular errors means?
You can simply read a brief explanation of it by hovering over its entry in the legend. Detailed information regarding this can be obtained by following the “More info” link in the tooltip.
Cesar Cuenca and Tiffany Wang who are Webmaster Tools interns at Google had this to say about site errors, “We hope that these changes will make Site errors even more information and helpful in keeping your site in tip-top shape.”
They added: “If you have any questions or suggestions, please let us know through the Webmaster Tools help Forum.”
Source: https://googlewebmastercentral.blogspot.com/2012/08/site-errors-breakdown.html