How does a captive portal work?

A captive portal works primarily by redirecting users to a specific web page where they must complete an authentication process before they are granted access to the network. This process is commonly used in public Wi-Fi hotspots or enterprise networks, ensuring that users agree to certain terms of service or enter login credentials before using the network resources.

When a device tries to connect to a network with a captive portal, it typically cannot access the internet directly until after interacting with the portal page. This method ensures that only authorized users can connect, which enhances security and helps manage network resources effectively. Furthermore, it allows network administrators to collect user information and track usage, which can be crucial for network management and legal compliance.

The other options describe functionalities that are not related to the specific mechanism of a captive portal. For instance, encrypting user data is a security measure, but it does not define how a captive portal operates. A virtual private network (VPN) serves a different purpose, as it provides secure, encrypted connections over the internet. Lastly, limiting access based on device type pertains to access control rather than the fundamental operation of a captive portal.