I am pretty sure you all heard about GoDaddy going offline yesterday afternoon for about four hours. In short, a hacker decided he wanted to teach GoDaddy a lesson and he took down their DNS.
It impacted millions of web sites that either host with GoDaddy or use GoDaddy as their domain name server (DNS).
But as an SEO, how did you handle the downtime? Honestly, the outage was so wide spread, I bet you didn't have to do anything.
Meaning, millions of sites were not loading and I am sure it spiked an alert at Google. Google probably took that into account when crawling web sites. So I doubt any site was negatively impacted in the search results due to the outage.
I am sure you lost four hours worth of traffic but did you see a drop in rankings?
I doubt that.
It would be interesting to see an official post from Google on how they handle situations like this. I suspect they may have decided to slow the crawlers a bit, somewhat like how they handled the black outs for SOPA.
John Mueller at Google responded to me on Google+ on how Google likely handled it saying:
With SOPA one problem was that sites put up different content and served it with a "200 OK", so it looked like they wanted to publish (and have found) that content. In this case, assuming it was just the DNS that wouldn't resolve, we would treat it similar to how we treat other temporary crawling issues, and just retry at some later point.