A botnet is a network of compromised computers controlled by an attacker. Botnets are often used to carry out Distributed Denial of Service (DDoS) attacks, where the compromised machines are directed to flood a target with traffic, rendering it inaccessible. References: Cisco Cybersecurity Operations Fundamentals, Module 1:
Security Concepts, Lesson 1.3: Common Network Application Operations and Attacks, Topic 1.3.4:
Denial-of-Service Attacks