Reasons for DDOS Attack -
Extortion - the attacker threatens an attack (perhaps with a demonstration), and demands money to avoid it.
Retaliation - the attacker is responding to something you did or said, or just doesn't like you.
Misdirection - the attack is intended to distract you from some other event (attack) elsewhere.
How to Prevent a DoS attack -
Purchase a lot of bandwidth - Though being a tough solution and also the most expensive one, it is beneficial. If tons of bandwidth is available, it becomes difficult for the attacker to generate a DoS attack because it's more bandwidth that an attacker has to clog.
Use DoS attack detection technology - Installing intrusion prevention system and firewall manufacturers also help prevent DoS as they include signature detection and connection verification techniques that limit the success of DoS attacks.
Prepare for DoS response - Using of controlling and rate-limiting technologies can reduce the DoS attack effects. When the DoS attack occurs one such response mode stops all new inbound connections, allowing continuation ofestablished connections and new outbound connections.
