Which AWS Shield level offers protection against DDoS attacks at no additional cost?

AWS Shield Standard provides protection against Distributed Denial of Service (DDoS) attacks at no additional cost as part of AWS services. This level of protection is automatically included for all AWS customers and focuses on safeguarding against the most common and frequently occurring types of DDoS attacks. The Shield Standard uses various techniques, like traffic engineering and anomaly detection, to detect and mitigate attacks in real-time, ensuring that your applications remain available and operational without the need for customer intervention.

It is important to note that while other services and levels, such as AWS Shield Advanced, provide enhanced features and additional support against DDoS attacks, they come with associated costs and are designed for higher-end protection against more sophisticated threats. AWS Firewall Manager and AWS Web Application Firewall serve different purposes, focusing primarily on managing security rules and even application layer protections, respectively, rather than serving as direct DDoS mitigation services.