KDC Realms refer to configurations within the Kerberos authentication protocol, where each realm is essentially a domain or network that operates under a single Key Distribution Center (KDC). This setup delineates a group of systems that are managed under the same master KDC, facilitating secure authentication and ticket-granting mechanisms across the network. Realms can be hierarchical or non-hierarchical, with the possibility of establishing trust relationships between them for secure inter-realm authentication .
The user interface provided in the ADC, as shown in the image above, allows you to define your Kerberos realms. This information can then be used within Authentication rules.
