In computing, a denial-of-service 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.
A distributed denial-of-service (DDoS) attack is one of the most powerful weapons on the internet. When you hear about a website being “brought down by hackers,” it generally means it has become a victim of a DDoS attack. In short, this means that hackers have attempted to make a website or computer unavailable by flooding or crashing the website with too much traffic.
Botnets can be comprised of almost any number of bots; botnets with tens or hundreds of thousands of nodes have become increasingly common, and there may not be an upper limit to their size. Once the botnet is assembled, the attacker can use the traffic generated by the compromised devices to flood the target domain and knock it offline.
DDoS attacks generally consist of attacks that fall into one or more categories, with some more sophisticated attacks combining attacks on different vectors. These are the categories:
Volume Based Attacks. These send massive amounts of traffic to overwhelm a network’s bandwidth.
Protocol Attacks. These are more focused and exploit vulnerabilities in a server’s resources.
Application Attacks. are the most sophisticated form of DDoS attacks, focusing on particular web applications.