Tomorrow 2017-02-02 the server hosting company has to shut down the root server for some minutes between 11:00 and 13:00 (Berlin server time UTC+1)
They will install some new power supplies in the server center.
I hope the server will restart fine after the power off.
I'll try to have a look in this timeframe from remote to see if the server is restarted properly.
In the worst case I'll have to fix something at the evening when I'm back at home.
In the best case the server will be offline for a short time only.
Subject: 
2017-02-01, 17:28