In some cases, it might not be that easy to detect an attack. For instance, in a suspected HTTP DDoS attack, a web server may be attacked with legitimate traffic, and therefore they are regular HTTP requests. This is where we can use HTTP DoS protection. HTTP DoS protection allows NetScaler to respond with a JavaScript challenge to all incoming HTTP requests. Now, since an HTTP DDoS attack is typically done using a cluster of multiple nodes running a scripted attack, these nodes do not support any form of JavaScript request. Therefore, when they cannot respond to the JavaScript challenge, NetScaler closes the connection. Regular users who surf through a regular browser that supports JavaScript are therefore granted access. This happens in the background, and the user never sees that it happens. Enabling HTTP DoS puts a lot of strain on NetScaler, especially if there is a lot of traffic and the client detect rate is at 100 percent.
To enable HTTP DoS, navigate to Security...