In computing, a denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is an attempt to make a machine or network resource unavailable to its intended users. Although the means to carry out, motives for, and targets of a DoS attack may vary, it generally consists of the efforts of one or more people to temporarily or indefinitely interrupt or suspend services of a host connected to the Internet. source: wikipedia"Flood Attack" is flooding a server, router or other device connected to the network with an enormous number of applications, which blocks the activity of the server by choking its Internet connection or making the processor to work extreme slowly. The concerted attack of several tens or hundreds of computers on the network server can easily be knelt. Generally server recovers only if the attack stops.
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