单选题 lA network attack is an attempt to gain（）access to an organization’s network,with the objective of stealing data or performing other malicious activities.Plagiarism is A（）-of-service（DoS）attack is a cyber-attack in which the attacker seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to a network.In the case of a simple attack,a（作答此空）could have a simple rule added to deny all incoming traffic from the attackers,based on protocols,ports,or the originating IP addresses.In a（）DoS（DDoS）attack ，the incoming traffic flooding the victim originates from（）different sources.This effectively makes it impossible to stop the attack simply by blocking a single source.