What is a Denial of Service (DoS) Attack?
With more than 2000 attacks observed globally on a daily basis, Denial of Service attacks present a very real threat to a wide variety of online services.
A DoS attack is a deliberate attempt to shut down a network. Typically the perpetrator uses one computer and one Internet connection to flood a targeted system or resource.
They work by either overwhelming the target with huge amounts of traffic (flood attacks) or sending information designed to trigger a crash (crashing services).
In both cases the DoS will render the network useless, denying all access to expected services or resources and creating major problems for its users.
Distributed Denial of Service Attack
A DDoS attack differs from a DoS attack in that the incoming traffic flooding the victim comes from a multitude of different sources. They generally target large, important resources such as banks.
Because of the high volume of traffic from multiple places, DDoS attacks make it difficult to determine legitimate traffic from attack traffic and of course, are harder to stop.
Any attack against server availability is deemed to be a Denial-of-Service attack. If a hacker uses many systems to launch attacks against a remote host, it is classed as a Distributed Denial of Service attack.