There are 2 offering of this service:

• FREE SERVICE, that is active for every AWS Customer.
• Provides protection from attacks such as SYN/UDP Flood, Reflective attacks, & other layer 3/4 attacks.

• Optional DDoS mitigation Service (3000$ per month/ organisation)
• Protect against more sophisticated attacks on EC2, ELB, CloudFront, Global Acclerator, Route53.
• 24/7 access to AWS DDoS response team.
• Protect against higher fees due to usage spike due to DDOS.