That's what a DDOS attack is to devs from ESO:
playstationlifestyle.net/2015/06/11/bethesda-conducts-elder-scrolls-online-ama-compares-launch-ddos-attack/
Here's a quote from there:
"Sage’s (posting as ZOS_Sage) response:
I’m going to answer your first bullet: login problems. Please be aware, we are doing everything we can do to make this experience better for everyone. And you are correct – these problems stem from incredible demand for the game. In fact, when we first turned the servers on at game launch, it was like we experienced a DDOS attack – there was so much demand from players that it completely overwhelmed everything. We’ve been working on fixing that ever since, and are getting to the point where we are managing everything through the queue, and login errors themselves are becoming less prevalent."
I'll let people draw their own conclusions...