Fragmentation attacks:
This is an attack that fights against the reassembling ability of the target. Numerous fragmented packets are sent to the target, making it difficult for the target to reassemble them; thereby, denying access to the valid clients.
TCP-State exhaustion attack:
The attacker sets up and tears down TCP connections and overwhelms the stable tables; thereby, causing a DOS attack.
Application Layer Attacks:
The attacker takes advantage of the programming errors in the application to cause the denial of service attack. It is achieved by sending numerous application requests to the target to exhaust the target’s resources so it will not be able to service any valid clients. A programming error in the case of buffer overflow attack- if the memory allocated to a variable is smaller than the requested, then it may lead to memory leakage or crashing the entire application.