The Dyn DDOS attack was committed using the Mirai source code released on the dark web earlier in October. It was an IOT attack. Cameras, and PVR’s were used to create a mass BOT network. This delivered over 300Gbps of DDOS attack at DYN and flattened it for a while. This then took out some big hitters in the Internet real-estate marker, Twitter, Spotify etc
A couple of good articles are here that go into more details.
What can we learn from this ? If firewalls that looked for application attacks and BOT networks had been place they would have spotted CNC traffic. For example Check Point Threat Prevention Blade, then you can stop your own network being infected by a BOT.