Esa, a malicious hacker, targeted an eccouncil video

Full Certification Question

Esa, a malicious hacker, targeted an organization’s cloud environment and created oversized HTTP requests to trick the origin web server into responding with error content, which can be cached at the CDN servers. The error-based content that is cached in the CDN server is delivered to legitimate users, resulting in a DoS attack on the target cloud environment. Which of the following attacks did Esa initiate in the above scenario?