Definition:
Denial of Service begins with a hacker who sends TCP-Transmission Control Protocol SYN-Synchronize message from a friendly site or "spoofed" with internal IP-Internet protocol Address. If target site is 198.20.0.0, hacker may send 198.20.0.255. In other words, hacker(s) appears to be internal or friendly users. Target (victim) responds with TCP ACK-SYN ACK-Acknowledgement - SYN-SYNchronize message.