A cooling problem in one of Wikipedia’s European data centers caused overheating in the facility that cascaded and eventually caused global outages to the site today, officials from the company reported.
“As this impacted all Wikipedia and other projects access from European users, we were forced to move all user traffic to our Florida cluster, for which we have a standard quick failover procedure in place, that changes our DNS entries,” according to the statement. It continued:
However, shortly after we did this failover switch, it turned out that this failover mechanism was now broken, causing the DNS resolution of Wikimedia sites to stop working globally. This problem was quickly resolved, but unfortunately it may take up to an hour before access is restored for everyone, due to caching effects.
We apologize for the inconvenience this has caused.