DDoS was the subject of a major project I had for one of my Master's courses. The year was 2006 and I was using this Dell Inspiron - good machine, but wasn't exactly top of the line. I needed to model a DDoS attack in a network simulation tool, basically using a few hundred zombies to attack this little web server for 60 seconds of simulation time, while a telecommuting user was trying to get on with a dial-up connection. The map and diagram as well as the theory was all rock solid. My instructor even commented on how thorough that was.
Then, I fired it up and let the fun begin.
Well, network simulator tools can be VERY processor intensive and that Core 2 processor instantly spiked to 100%. So, I let the simulator run - all night. Mind you the simulation was for a sixty-second attack, but the calculations churned away. It took about 12 hours in real time to complete the simulation. I got a nice pile of telemetry from the test, but I think my network simulator did its own version of realism - and sprung a DDoS attack of its own.
Good times.