Cookie Challenge

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Cookie Challenge, also known as Cookie Validation, is a type of web challenge that is used in DDoS mitigation to filter out attackers from legitimate clients. The cookie challenge is to send every client, attacker and legitimate user a web cookie and to request that the client send it back (typically using the HTTP 302 Redirect command). A virtually legitimate browser supports web cookies and will easily pass the cookie challenge transparently (without the user’s notice), while DDoS bots typically don’t save cookies and therefore cannot pass the challenge.