Cisco ISE supports two types of WebAuth for BYOD: central WebAuth and local WebAuth. Central WebAuth is the default method and it uses the ISE portal to authenticate the users and redirect them to the BYOD portal. Local WebAuth is an alternative method that uses the network access device (NAD) portal to authenticate the users and then redirects them to the ISE BYOD portal. Both methods require the configuration of a guest component on ISE, which is used to create the BYOD portal and the guest user accounts. The guest component also provides the self-service onboarding and registration features for the BYOD users. The dual component is not related to BYOD, but rather to the dual-SSID method, which uses two separate SSIDs for provisioning and access. The null WebAuth component is not a valid option for BYOD. References := Some possible references are:
* Cisco ISE BYOD Prescriptive Deployment Guide
* Configure Single SSID Wireless BYOD on Windows and ISE
* Cisco ISE for BYOD and Secure Unified Access, 2nd Edition