A Denial-of-Service (DoS) attack is mounted with the objective of causing a negative impact on the performance of a computer or network. It is also known as network saturation attack or bandwidth consumption attack. Attackers perform DoS attacks by sending a large number of protocol packets to a network. The problems caused by a DoS attack are as follows:

l Saturation of network resources

l Disruption of connections between two computers, thereby preventing communications between services

l Disruption of services to a specific computer

l Failure to access a Web site

l Increase in the amount of spam

Which of the following can be used as countermeasures against DoS attacks?

Each correct answer represents a complete solution. Choose all that apply.