Recently we have seen that Google sending messages to webmasters if there is problem in DNS or Server connectivity.
Google has made some more changes and started giving more detailed break down of these errors:
- Lookup error
- Timeout
- Total DNS errors
Lookup error
DNS Lookup means that Google is not able to access your site due to the fact that your DNS server did not recognize your hostname (such as www.submitshop.com)
Timeout
It means that Google couldn’t access your website due to DNS server did not recognize your hostname (such as www.submitshop.com).
Total DNS errors
Googlebot is not able to crawl or fetch your site because Google is not able to communicate with the DNS server, or because your server had no entry for your site. It may due to server downtime, or DNS routing to your website.
It will be more helpful for webmasters who are non technical with server or DNS related factors and help to reduce down time of website.
References
http://googlewebmastercentral.blogspot.com/2012/08/site-errors-breakdown.html