Establishing a trust relationship between realms creates a shortcut for authentication.
This function is optional because by default the Kerberos protocol searches the realm hierarchy looking for trust. This function is useful if you have realms in different domains and want to make this process faster. To set up realm trust, each Kerberos server for each realm must share a key. Before you create a trust relationship in network authentication service, set up the Kerberos servers to trust one another. To create a trust relationship among realms, follow these steps: