When hackers flood a Web site with useless traffic to overwhelm the network, it is called ______.

When hackers flood a Web site with useless traffic to overwhelm the network, it is called a Denial of Service (DoS) attack. A denial-of-service attack (DoS attack) is a cyber-attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to the Internet.