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I was just checking Google Webmaster Tools for one of the first times (I know this should have been a regular habit). I noticed that on Feb 8th we had almost 80K errors of type 503.  This is obviously very alarming because as far as I know our site was up and available that whole day.  This makes me wonder if there is a firewall issue or something else that I'm not aware of. Any ideas for the best way to determine what's causing this? Thanks, Chris