Ask HN: How does online Ticket queuing system works?

I go to a fair amount of music festivals and purchase tickets online. But I never really paid attention to how they manage all that traffic load and queues. I recently read this article http://www.mixmag.net/words/news/hackers-who-jumped-burning-man-ticket-queue-caught and was wondering how the system is constructed. If anyone can refer me to a good article about the system, I would really appreciate it :)