which of the following is not an example of a non-commercial Spam ?
Spam as denial of service is not an example of a non-commercial Spam.
A distributed denial-of-service (DDoS) attack occurs when an assailant uses your computer, in concert with many others, to assault a target endpoint. The hacker exploits security weaknesses and takes control of your computer to send spam to other email addresses.
A denial-of-service (DoS) is any type of attack where the attackers (hackers) attempt to prevent legitimate users from accessing the service. In a DoS attack, the attacker usually sends excessive messages asking the network or server to authenticate requests that have invalid return addresses.
Distributed DoS attack. A distributed denial-of-service (DDoS) attack occurs when multiple systems flood the bandwidth or resources of a targeted system, usually one or more web servers. Such an attack is often the result of multiple compromised systems (for example, a botnet) flooding the targeted system with traffic.