Since November 14th, I've been seeing a large uptick in complaints about Google Webmaster Tools reporting DNS issues with sites, leading to Google not being able to index sites fully.
There is a thread at WebmasterWorld and dozens at Google Webmaster Help.
In April, Google had a bug where they sent out false DNS errors to many webmasters and told everyone to ignore them. I am not sure if this is an issue with Google or something else.
The strange part is that it coincides with reports of ranking changes that I don't see myself.
I am going to try to get word from Google about the DNS issue and see if it was a bug and/or if it may be in any way related to the changes some tools noticed in regards to ranking fluctuations on November 14th.
Forum discussion at WebmasterWorld and dozens at Google Webmaster Help.
Update: Google told me, "we're not seeing anything unusual on our end." :-)
