Yesterday, 2 April, around 22:25 our systems we subject to a large attack. We managed to block most of it quickly. Around 23:15 it seemed the attack was defeated fully.
In blocking the attack we made some configuration changes that caused other problems. We inadvertently blocked our internal DNS servers, resulting in (after a small delay) websites not being able to connect to databases, and webmail not being able to connect to it's database. These problems became clear a little past midnight. At 01:10 these issues were fixed too.
We apologize for the disruption. We will evaluate what went wrong and see what we can do to prevent similar incidents from happening again.