What is often a target of a Denial of Service attack?

A Denial of Service (DoS) attack is designed to make a service unavailable to its intended users by overwhelming it with a flood of illegitimate requests or exploiting vulnerabilities. This means that multiple types of services can be targeted, making all the listed options valid.

Websites are commonly targeted because they are directly accessed by users and can face significant disruptions when overwhelmed with traffic. Database servers can also be a target since they manage data for applications; an attack can disrupt data accessibility. Email systems, being vital for communication, can be bombarded with requests, causing delays or complete outages.

Since all these systems rely on network availability and functionality, they each represent valid targets for denial of service attacks. Therefore, indicating that all of the options can be targeted effectively captures the breadth of potential vulnerabilities in various services.