Selected answers from the Dumb SEO Questions G+ community.
Dave Elliott: check your robots.txt file to see if an important page or even the google bot itself is disallowed. Also, if you can then check to see if your site experienced any down time.
True Vision Technologies: I would like to ask Is the message about DNS error appears all time in webmaster tools page or its appear only when you hover on DNS graphics.. If you only see while hover over the graphics than just ignore it.
Weblinx: What + said is pretty much the case. However, this can also happen for recently changed domains where the DNS hasn`t fully propagated around the world.<br /><br />How long have you been noticing this problem?
Andrei Gherghelv: + if your website is loading than it was probably just a temporary issue with the server where your website is hosted. It happens sometimes, maybe the server was restarted. + made a good point but you get your website in WMT only after you get verified as owner/admin of the website. Most people do it by uploading a file or adding a meta tag. In this case the website was already working and the DNS propagation period already passed.
Jim Munro: Hi Rajeev. One thing I noticed was that your dns expiry time is half recommended and four times less than what most people use. It`s probably not your issue but are you able to change this?