Date Added: Apr 2013
A DoS (Denial of Service) attack is characterized by an explicit attempt to prevent the legitimate use of a service. These attacks overwhelm the processing or link capacity of the target sites by saturating them with bogus packets. Such attacks can seriously disrupt legitimate communications. These attacks can disrupt the availability of Internet services completely, by eating either computational or communication resources through sheer volume of packets sent from distributed locations in a coordinated manner or graceful degradation of network performance by sending attack traffic at low rate. Distributed Denial of Service (DDoS) Attacks, when an attacker attacks from multiple source systems, it is called a Distributed Denial of Service (DDoS) attack.