How is a denial of service attack mounted and carried out?

Answer 1

It is a 3 staged approach:

Stage 1 - Infect computers with programs such as Trojans that will allow remote access to take over control or initiate a program to perform a specific task(s). This will convert the computer to become a botnet.

Stage 2 - Collect botnets - so that the bot master will be able to make all the botnets to perform a specific task simultaneously.

Stage 3 - Perform DDoS (Distributed Denial of Service) attack! The bot master will activate his/her botnets to perform the denial of service (DOS) attack.