Which NAC type involves redirecting users to comply with authentication requirements?

The choice of Captive Portal as the correct answer is based on its function in a network access control (NAC) environment. A Captive Portal is specifically designed to intercept a user's network traffic and redirect them to a web page where they're required to authenticate or agree to certain terms before being granted full access to the network.

This method is commonly used in environments such as public Wi-Fi networks, where users need to log in through the portal to gain internet access. The redirection ensures that users are presented with the necessary authentication requirements before they can access network resources. This approach effectively enforces compliance with security protocols and offers a layer of control over who can use the network.

In contrast, other options like Quarantine Portal involve isolating devices that do not meet certain security standards, Dissolvable NAC refers to software that is downloaded for temporary use to enforce security compliance, and Permanent NAC entails ongoing management of devices that have persistent compliance without requiring redirection. These functionalities do not involve the same redirection mechanism that Captive Portals utilize for authentication compliance.