What type of attack involves overwhelming a server with traffic?

A Denial-of-Service (DoS) attack is characterized by overwhelming a server or network with a flood of traffic, rendering it unable to respond to legitimate users. This type of attack exploits the server's resources, such as CPU, memory, and bandwidth, leading to degraded performance or complete unavailability of the targeted service.

In a DoS attack, the goal is to deprive users of access and disrupt normal operations. Attackers may use various methods, including sending numerous requests to the server or exploiting vulnerabilities in the server’s software. The key element of this attack type is the intent to incapacitate a service by saturating its capacity, causing it to crash or slow down significantly.

Other types of attacks mentioned do not fit this description. For instance, a Man-in-the-Middle attack involves intercepting and altering communications between two parties without their knowledge. Phishing attacks are aimed at tricking individuals into divulging sensitive information, typically through deceptive emails or websites. SQL Injection abuses vulnerabilities in web applications to execute unauthorized SQL commands, rather than overwhelming resources. Each of these attacks has distinct mechanics and objectives that differ substantially from a DoS attack.