Quiz - Designing URL Shortner

Preventing Malicious URL Key Use

How can the system prevent a single malicious user from consuming all available URL keys?

"By implementing rate limiting on URL creations and redirections."

While rate limiting the redirections on a single URL is generally a good idea, redirect rate limiting is a separate protection against abusive traffic and does not prevent URL-key consumption. It's not answering the question. We rate limit the URL creations to prevent somebody from consuming all available URL keys. The answer should align with the question; this one does not. Also it's not clear whether it's asking about protecting a users limit on URL creations or all API keys in general. I know from reading the editorial that it's the former, but the question should be more clear about that