DoS and DDoS attacks 

A Denial-of-Service is an attack in which online services do not respond to connections from legitimate hosts due to their resources being overused by malicious requests. This attack becomes a Distributed Denial-of-Service (DDoS) attack when it comes from multiple sources and it becomes difficult to block the source with IP or Geo-location.

DDoS attacks usually take the form of the following:

• Volume-based attacks
• Application layer attacks
• Low-rate attacks

Volume-based attacks

Volume based attacks are by far the most common type of DDoS attacks.

Note

According to Arbor Networks, 65% of DDoS attacks are volumetric in nature.

Volume-based attacks are characterized by an excessive amount of traffic (sometimes in excess of 100 Gbps). They do not mandate large amounts of traffic to be generated by one location or one source.

The following is an example of such an attack:

• NTP Amplification: The NTP amplification attack is a volume based DDoS attack in which an attacker exploits the publicly...