Explain what a denial-of-service attack is, including the terms DDOS and zombie army in your response.

What will be an ideal response?

A denial-of-service (DoS) attack is typically directed at a business or government website. The attack automatically directs browsers, usually on many machines, to a single web address at roughly the same time. The result causes so much network traffic to the targeted site that it is effectively shut down to legitimate users. Although such an attack is seldom directed toward an individual's computer, the resulting effect can still inconvenience individual users of the targeted website. (Spam can accomplish a similar, but less targeted effect, by flooding the Internet with junk email messages that consume available bandwidth and clog mail servers.) If many machines are perpetrating this mischief, it's called a distributed denial-of-service attack, or DDOS. A DDOS may use thousands of machines, enabling much heavier attack traffic and at the same time making it harder to track down and disable all of the attacking machines. Many times, these machines are personal computers that were infected at some point by a Trojan horse. Then at a later time, the Trojan horse is activated in all these machines, putting them under the command of a single controller. This collection of machines is sometimes called a zombie army or botnet (short for "robot network" because the machines act like robots under someone else's control).