Example: http://getpersonas-cdn.mozilla.net/static_json/1/2/453212/preview.jpg?1326697642 That returns "Server not found" for me. We've gotten a bunch of reports of this from other places in the last couple days. Not sure if it's intermittent.
This should be resolved now. This was pointing at Edgecast, CDNetworks, and Internap. Internap was a trial, and apparently just shut it off on us (or is otherwise broken for our particular CNAME). Cedexis knows if a CDN has problems, but not our *specific* account as we don't use our own Radar data. That means they don't know if we, for example, stop paying the bill and a CDN shuts us off, which is effectively what seems to have happened here. :)