A denial-of-service (DoS) or distributed denial-of-service (DDoS) attack is a malicious attempt to disrupt normal traffic of a targeted server, service, or network by overwhelming the target or its surrounding infrastructure with a flood of Internet traffic. There are several types of DDoS attacks, for example, HTTP flood, SYN flood, DNS amplification, etc.
In RouterOS, we have to split DoS/DDoS protection into 2 parts: detection and processing.