Api outage

The api server has been unavailable some time this morning (UTC) due to a backend error. Our monitoring did not notice the problem thus we are not certain for how long it was unavailable. All other validation servers worked fine, so if you used the version 2 validation protocol you should not have experienced any service interruption.

Update: The problem appears to have been caused by a client misbehavior that led to what looked like a DoS attack. We have applied network filtering to resolve the current problem.